A prospective study of calciotropic hormones in pregnancy and post partum: reciprocal changes in serum intact parathyroid hormone and 1,25-dihydroxyvitamin D

Physiological Changes in Pregnant Women Due to Hormonal Changes

Pregnancy affects many organ systems and causes significant physiological changes that are mainly caused by changes in hormone levels. This review explores the complex interactions between pregnancy-related hormonal changes and renal function, providing insights into the practical applications of these relationships. Extensive literature searches were conducted, combining data from several sources to produce thorough knowledge. Essential discoveries include changes in renal hemodynamics, calcium/phosphorus level variations, thyroid gland hypertrophy, changed function, and cardiovascular adaptations. The review also addresses how sex hormones affect immunological responses, emphasizing their importance for conditions like multiple sclerosis. Additionally impacted is the gastrointestinal tract, which results in symptoms like nausea and heartburn. Comprehending these physiological changes is essential for proficient therapeutic handling, guaranteeing the best possible health for both the mother and the fetus. The study emphasizes the importance of specialized medical treatment during pregnancy and calls for more investigation to clarify the intricacies of these physiological changes.

Management of Hypoparathyroidism

Hypoparathyroidism (HypoPT) is a rare disorder characterized by hypocalcemia in the presence of a low or inappropriately normal parathyroid hormone level. HypoPT is most commonly seen after neck surgery, which accounts for approximately 75% of cases, whereas approximately 25% have HypoPT due to nonsurgical causes. In both groups of patients, conventional therapy includes calcium and active vitamin D analogue therapy aiming to maintain serum calcium concentration in the low normal or just below the normal reference range and normalize serum phosphorus, magnesium concentrations, and urine calcium levels. The limitations of conventional therapy include wide fluctuations in serum calcium, high pill burden, poor quality of life, and renal complications. Parathyroid hormone (PTH) replacement therapy may improve the biochemical profile in those in whom conventional therapy proves unsatisfactory. Based on a systematic review and meta-analysis of the literature, the panel made a graded recommendation suggesting conventional therapy as first line therapy rather than administration of PTH (weak recommendation, low quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers use of PTH. Because pregnancy and lactation are associated with changes in calcium homeostasis, close monitoring is required during these periods with appropriate adjustment of calcium and active vitamin D analogue therapy to ensure that serum calcium remains in the mid to low normal reference range in order to avoid maternal and fetal complications. Emerging therapies include molecules with prolonged PTH action as well as different mechanisms of action that may significantly enhance drug efficacy and safety. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Evaluation and Management of Hypoparathyroidism Summary Statement and Guidelines from the Second International Workshop

This clinical practice guideline addresses the prevention, diagnosis, and management of hypoparathyroidism (HypoPT) and provides evidence-based recommendations. The HypoPT task forces included four teams with a total of 50 international experts including representatives from the sponsoring societies. A methodologist (GG) and his team supported the taskforces and conducted the systematic reviews. A formal process following the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology and the systematic reviews provided the structure for seven of the guideline recommendations. The task force used a less structured approach based on narrative reviews for 20 non-GRADEd recommendations. Clinicians may consider postsurgical HypoPT permanent if it persists for >12 months after surgery. To predict which patients will not develop permanent postsurgical HypoPT, we recommend evaluating serum PTH within 12 to 24 hours post total thyroidectomy (strong recommendation, moderate quality evidence). PTH > 10 pg/mL (1.05 pmol/L) virtually excludes long-term HypoPT. In individuals with nonsurgical HypoPT, genetic testing may be helpful in the presence of a positive family history of nonsurgical HypoPT, in the presence of syndromic features, or in individuals younger than 40 years. HypoPT can be associated with complications, including nephrocalcinosis, nephrolithiasis, renal insufficiency, cataracts, seizures, cardiac arrhythmias, ischemic heart disease, depression, and an increased risk of infection. Minimizing complications of HypoPT requires careful evaluation and close monitoring of laboratory indices. In patients with chronic HypoPT, the panel suggests conventional therapy with calcium and active vitamin D metabolites as first-line therapy (weak recommendation, low-quality evidence). When conventional therapy is deemed unsatisfactory, the panel considers the use of PTH. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Physiological Changes in Serum Calcium, Phosphate, Vitamin D, Parathyroid Hormone and Calcitonin During Pregnancy and Lactation in Randomised Population of Zaria Women

Pregnancy and lactation are usual but stressful physiological conditions accompanied by changes in calcium and phosphate metabolism and their regulatory hormones which may lead to calcium-related disorders in pregnant women. This study aimed to evaluate the changes in serum levels of calcium, phosphate, vitamin D and their regulatory hormones in pregnant and lactating women in Zaria, Nigeria. A cross‑sectional descriptive study was conducted at Ahmadu Bello University Teaching Hospital, Zaria for three (3) months. Blood samples were collected, anthropometric measurements (weight, height and body mass index) of 179 women were taken. Serum calcium, phosphate, vitamin D, parathyroid hormone and calcitonin were determined using standard methods. Data were presented as mean ± SD, analysis was performed using one-way ANOVA and Pearson's correlation analysis. Values were considered significant at p ≤ 0.05. There was a significant decrease in serum calcium concentration (p < 0.01) during the third trimester of pregnancy and lactation. An increase in serum concentration of vitamin D, parathyroid hormone, and calcitonin in the 2nd trimester and a decrease during the third trimester and lactation although not statistically significant when compared with the control. There was a negative correlation between serum calcium concentration and gestational age (r = 0.255) while no correlation between gestational age and serum phosphate concentration. Changes in serum calcium, vitamin D, parathyroid hormone and calcitonin during pregnancy and lactation has been demonstrated suggesting a relationship between calcium metabolism and these hormones at some stages of pregnancy.

Physiological changes in pregnancy and their influence on the endocrine investigation

BACKGROUND

Physiological changes in pregnancy may result in significant alterations in endocrine hormone profiles, serum and urine electrolytes and endocrine gland morphology on imaging. Pregnancy-specific pathophysiological processes may also affect the results for endocrine tests. Investigation of endocrine disorders in pregnancy requires knowledge of these changes and awareness of the safety of dynamic hormone testing and imaging for the mother and foetus.

OBJECTIVE

This review seeks to outline the important physiological changes in pregnancy affecting reference intervals of basal and dynamic endocrine tests in pregnancy and the scenarios in which these changes are clinically significant, the pregnancy-specific disorders that may affect the investigation of endocrine disorders, and the safety of dynamic testing and imaging.

CONCLUSION

Awareness of the effect of physiological changes, and the potential impact of pregnancy-specific disorders of endocrine tests, and the safety of imaging is crucial to the management of endocrine disorders in pregnancy.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Maternal and fetal vitamin D and their roles in mineral homeostasis and fetal bone development

During pregnancy, female physiology adapts to meet the additional mineral demands of the developing fetus. Meanwhile, the fetus actively transports minerals across the placenta and maintains high circulating levels to mineralize the rapidly developing skeleton. Most of this mineral is accreted during the last trimester, including 30 g of calcium, 20 g of phosphate and 0.8 g of magnesium. Given the dependence of calcium homeostasis on vitamin D and calcitriol in the adult and child, it may be expected that vitamin D sufficiency would be even more critical during pregnancy and fetal development. However, the pregnant mother and fetus appear to meet their mineral needs independent of vitamin D. Adaptations in maternal mineral and bone metabolism during pregnancy appear to be invoked independent of maternal vitamin D, while fetal mineral metabolism and skeletal development appear to be protected from vitamin D deficiency and genetic disorders of vitamin D physiology. This review discusses key data from both animal models and human studies to address our current knowledge on the role of vitamin D and calcitriol during pregnancy and fetal development.

Hypoparathyroidism in Pregnancy and Lactation: Current Approach to Diagnosis and Management

Background: Hypoparathyroidism is an uncommon endocrine disorder. During pregnancy, multiple changes occur in the calcium-regulating hormones, which may affect the requirements of calcium and active vitamin D during pregnancy in patients with hypoparathyroidism. Close monitoring of serum calcium during pregnancy and lactation is ideal in order to optimize maternal and fetal outcomes. In this review, we describe calcium homeostasis during pregnancy in euparathyroid individuals and also review the diagnosis and management of hypoparathyroidism during pregnancy and lactation. Methods: We searched the MEDLINE, CINAHL, EMBASE, and Google scholar databases from 1 January 1990 to 31 December 2020. Case reports, case series, book chapters, and clinical guidelines were included in this review. Conclusions: During pregnancy, rises in 1,25-dihydroxyvitamin D (1,25-(OH)2-D3) and PTH-related peptide result in suppression of PTH and enhanced calcium absorption from the bowel. In individuals with hypoparathyroidism, the requirements for calcium and active vitamin D may decrease. Close monitoring of serum calcium is advised in women with hypoparathyroidism with adjustment of the doses of calcium and active vitamin D to ensure that serum calcium is maintained in the low-normal to mid-normal reference range. Hyper- and hypocalcemia should be avoided in order to reduce the maternal and fetal complications of hypoparathyroidism during pregnancy and lactation. Standard of care therapy consisting of elemental calcium, active vitamin D, and vitamin D is safe during pregnancy.

Higher maternal parathyroid hormone concentration at delivery is not associated with smaller newborn size

Intrauterine growth restriction (IUGR) reflects inadequate growth in-utero and is prevalent in low resource settings. This study aimed to assess the association of maternal delivery parathyroid hormone (PTH) - a regulator of bone turnover and calcium homeostasis - with newborn anthropometry, to identify regulators of PTH, and to delineate pathways by which maternal PTH regulates birth size using path analysis. This was a cross-sectional analysis of data from participants (n = 537) enrolled in the Maternal Vitamin D for Infant Growth trial in Dhaka, Bangladesh. Primary exposures were maternal delivery intact PTH (iPTH) or whole PTH (wPTH) and outcomes were gestational age- and sex-standardized z-scores for birth length (LAZ), weight (WAZ), and head circumference (HCAZ). Hypothesized regulators of PTH included calcium and protein intake, vitamin D, magnesium, fibroblast-like growth factor-23 (FGF23), and C-reactive protein. Maternal iPTH was not associated with birth size in linear regression analyses; however, in path analysis models, every SD increase in log(iPTH) was associated with 0.08SD (95% CI: 0.002, 0.162) higher LAZ. In linear regression and path analysis models, wPTH was positively associated with WAZ. Vitamin D suppressed PTH, while FGF23 was positively associated with PTH. In path analysis models, higher magnesium was negatively associated with LAZ; FGF23 was positively associated and protein intake was negatively associated with LAZ, WAZ, and HCAZ. Higher maternal PTH in late pregnancy is unlikely to contribute to IUGR. Future studies should investigate maternal FGF23, magnesium and protein intake as regulators of fetal growth, particularly in settings where food insecurity and IUGR are public health problems.

Parathyroid Hormone in Pregnancy: Vitamin D and Other Determinants

We aimed to assess the parathyroid hormone (PTH) concentration in pregnant women at the beginning of pregnancy (1st trimester) and within days before delivery (3rd trimester) and evaluate its determinants. From September 2014 through December 2015 in a cross-sectional study, 204 women in the 1st trimester of pregnancy and 203 women in the 3rd trimester of pregnancy were recruited. Blood samples were collected to measure PTH and circulating 25-hydroxy-vitamin D (25(OH)D) concentrations. Lifestyle and demographic data were collected using a questionnaire. Serum 25(OH)D and PTH were inversely correlated in both early and late pregnancy. Our analyses suggest that in the 3rd trimester of pregnancy, a 25(OH)D level of 18.9 ng/mL (47.3 nmol/L) could serve as an inflection point for the maximal suppression of PTH. Statistically significant determinants of PTH concentrations in multiple regression were 25(OH)D concentrations, season, multiparity and education of the partner (all p < 0.05) in early pregnancy. In late pregnancy, 25(OH)D concentrations and country of origin were statistically significant determinants of PTH concentrations (all p < 0.05). These factors and their effect on PTH appear to be vastly determined by 25(OH)D; however, they might also affect PTH through other mechanisms besides 25(OH)D.

Familial Hypocalciuric Hypercalcemia in Pregnancy: Diagnostic Pitfalls

Familial hypocalciuric hypercalcemia (FHH) is a group of autosomal dominant disorders caused by dysfunction of the calcium sensing receptor (CaSR) and its downstream signaling proteins, leading to generally asymptomatic hypercalcemia. During pregnancy, distinguishing FHH from primary hyperparathyroidism (PHPT) is important, as the latter is associated with adverse outcomes and can be treated surgically during pregnancy, whereas the former is benign. This case report highlights the difficulties in diagnosing FHH during pregnancy. A 32‐year‐old woman was found to have asymptomatic hypercalcemia at 14‐weeks’ gestation. Investigations showed a corrected calcium (cCa) of 2.61 mmol/L (2.10 to 2.60), ionized Ca (iCa) of 1.40 mmol/L (1.15 to 1.28), 25OHD of 33 nmol/L (75 to 250), and PTH of 9.5 pmol/L (1.5 to 7.0). The patient was treated with 2000 IU cholecalciferol daily with normalization of 25OHD. The urine calcium / creatinine clearance ratio (CCCR) was 0.0071, and neck US did not visualize a parathyroid adenoma. Upon a retrospective review of the patient's biochemistry from 2 years prior, hypercalcemia was found that was not investigated. The patient was monitored with serial iCa levels and obstetric US. She delivered a healthy boy at 38‐weeks’ gestation. Postnatal iCa was 1.48 mmol/L and remained elevated. Her son had elevated iCa at birth of 1.46 mmol/L (1.15 to 1.33), which rose to 1.81 mmol/L by 2 weeks. He was otherwise well. Given the familial hypercalcemia, a likely diagnosis of FHH was made. Genetic testing of the son revealed a missense mutation, NM_000388.3(CASR):c.2446A > G, in exon 7 of the CaSR, consistent with FHH type 1. To our knowledge, there are only three existing reports of FHH in pregnancy. When differentiating between FHH and PHPT in pregnancy, interpretation of biochemistry requires an understanding of changes in Ca physiology, and urine CCCR may be unreliable. If the decision is made to observe, clinical symptoms, calcium levels, and fetal US should be monitored, with biochemistry and urine CCCR performed postpartum, once lactation is completed © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Standards of care for hypoparathyroidism in adults: a Canadian and International Consensus

PURPOSE

To provide practice recommendations for the diagnosis and management of hypoparathyroidism in adults.

METHODS

Key questions pertaining to the diagnosis and management of hypoparathyroidism were addressed following a literature review. We searched PubMed, MEDLINE, EMBASE and Cochrane databases from January 2000 to March 2018 using keywords 'hypoparathyroidism, diagnosis, treatment, calcium, PTH, calcidiol, calcitriol, hydrochlorothiazide and pregnancy'. Only English language papers involving humans were included. We excluded letters, reviews and editorials. The quality of evidence was evaluated based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. These standards of care for hypoparathyroidism have been endorsed by the Canadian Society of Endocrinology and Metabolism.

RESULTS

Hypoparathyroidism is a rare disease characterized by hypocalcemia, hyperphosphatemia and a low or inappropriately normal serum parathyroid hormone level (PTH). The majority of cases are post-surgical (75%) with nonsurgical causes accounting for the remaining 25% of cases. A careful review is required to determine the etiology of the hypoparathyroidism in individuals with nonsurgical disease. Hypoparathyroidism is associated with significant morbidity and poor quality of life. Treatment requires close monitoring as well as patient education. Conventional therapy with calcium supplements and active vitamin D analogs is effective in improving serum calcium as well as in controlling the symptoms of hypocalcemia. PTH replacement is of value in lowering the doses of calcium and active vitamin D analogs required and may be of value in lowering long-term complications of hypoparathyroidism. This manuscript addresses acute and chronic management of hypoparathyroidism in adults.

MAIN CONCLUSIONS

Hypoparathyroidism requires careful evaluation and pharmacologic intervention in order to improve serum calcium and control the symptoms of hypocalcemia. Frequent laboratory monitoring of the biochemical profile and patient education is essential to achieving optimal control of serum calcium.

Randomized trial of three doses of vitamin D to reduce deficiency in pregnant Mongolian women

BACKGROUND

In winter in Mongolia, 80% of adults have 25-hydroxyvitamin D (25(OH)D) concentrations <25 nmol/l (<10 ng/ml) and 99% have <50 nmol/l (<20 ng/ml). The vitamin D dose to avert deficiency during pregnancy in this population is unknown.

METHODS

We conducted a randomized, controlled, double-blind trial of daily 600, 2000, or 4000 IU vitamin D₃ for pregnant women in Mongolia (Clinicaltrials.gov #NCT02395081). We examined 25(OH)D concentrations at baseline (12-16 weeks' gestation), 36-40 weeks' gestation and in umbilical cord blood, using enzyme linked fluorescent assay. Sample size was determined to detect 0.4 standard deviation differences in 25(OH)D concentrations with 80% power.

FINDINGS

119 pregnant women were assigned 600 IU, 121 assigned 2000 IU and 120 assigned 4000 IU from February 2015 through December 2016. Eighty-eight percent of participants took ≥80% of assigned supplements. At baseline, 25(OH)D concentrations were similar across arms; overall mean ± standard deviation concentration was 19 ± 22 nmol/l; 91% were < 50 nmol/l. At 36-40 weeks, 25(OH)D concentrations increased to 46 ± 21, 70 ± 23, and 81 ± 29 nmol/l for women assigned 600, 2000, and 4000 IU, respectively (p < 0.0001 across arms; p = 0.002 for 2000 vs. 4000 IU). Mean umbilical cord 25(OH)D concentrations differed by study arm (p < 0.0001 across arms; p < 0.0001 for 2000 vs. 4000 IU) and were proportional to maternal concentrations. There were no adverse events, including hypercalcemia, attributable to vitamin D supplementation.

INTERPRETATION

Daily supplementation of 4000 IU during pregnancy is safe and achieved higher maternal and neonatal 25(OH)D concentrations than 2000 IU. Daily 600 IU supplements are insufficient to prevent vitamin D deficiency in Mongolia. FUND: Anonymous foundation and Brigham and Women's Hospital.

Changes in biochemical tests in pregnancy and their clinical significance

Interpretation of laboratory investigations relies on reference intervals. Physiological changes in pregnancy may result in significant changes in normal values for many biochemical assays, and as such results may be misinterpreted as abnormal or mask a pathological state. The aims of this review are as follows: 1. To review the major physiological changes in biochemical tests in normal pregnancy. 2. To outline where these physiological changes are important in interpreting laboratory investigations in pregnancy. 3. To document the most common causes of abnormalities in biochemical tests in pregnancy, as well as important pregnancy-specific causes.

Making (mis) sense of asymptomatic marked hypercalcemia in pregnancy

We describe a rare case of homozygous inactivating calcium‐sensing receptor mutation detected during pregnancy and mimicking primary hyperparathyroidism. In pregnancy, the differential diagnosis of hypercalcaemia requires a cautious approach as physiological changes in calcium homeostasis may mask rare genetic conditions.

The role of vitamin D in pre-eclampsia: a systematic review

BACKGROUND

The etiology of pre-eclampsia (PE) is not yet fully understood, though current literature indicates an upregulation of inflammatory mediators produced by the placenta as a potential causal mechanism. Vitamin D is known to have anti-inflammatory properties and there is evidence of an inverse relationship between dietary calcium intake and the incidence of PE. Evidence of the role of vitamin D status and supplementation in the etiology and prevention of PE is reviewed in this article along with identification of research gaps to inform future studies.

METHODS

We conducted a structured literature search using MEDLINE electronic databases to identify published studies until February 2015. These sources were retrieved, collected, indexed, and assessed for availability of pregnancy-related data on PE and vitamin D.

RESULTS

Several case-control studies and cross-sectional studies have shown an association between vitamin D status and PE, although evidence has been inconsistent. Clinical trials to date have been unable to show an independent effect of vitamin D supplementation in preventing PE.

CONCLUSIONS

The included clinical trials do not show an independent effect of vitamin D supplementation in preventing PE; however, issues with dose, timing, and duration of supplementation have not been completely addressed.

How the reference values for serum parathyroid hormone concentration are (or should be) established?

Well-validated reference values are necessary for a correct interpretation of a serum PTH concentration. Establishing PTH reference values needs recruiting a large reference population. Exclusion criteria for this population can be defined as any situation possibly inducing an increase or a decrease in PTH concentration. As recommended in the recent guidelines on the diagnosis and management of asymptomatic primary hyperparathyroidism, PTH reference values should be established in vitamin D-replete subjects with a normal renal function with possible stratification according to various factors such as age, gender, menopausal status, body mass index, and race. A consensus about analytical/pre-analytical aspects of PTH measurement is also needed with special emphasis on the nature of the sample (plasma or serum), the time and the fasting/non-fasting status of the blood sample. Our opinion is that blood sample for PTH measurement should be obtained in the morning after an overnight fast. Furthermore, despite longer stability of the PTH molecule in EDTA plasma, we prefer serum as it allows to measure calcium, a prerequisite for a correct interpretation of a PTH concentration, on the same sample. Once a consensus is reached, we believe an important international multicentre work should be performed to recruit a very extensive reference population of apparently healthy vitamin D-replete subjects with a normal renal function in order to establish the PTH normative data. Due to the huge inter-method variability in PTH measurement, a sufficient quantity of blood sample should be obtained to allow measurement with as many PTH kits as possible.

A study of bone turnover markers in gestational diabetes mellitus

INTRODUCTION

Gestational diabetes is defined as carbohydrate intolerance resulting in hyperglycemia of variable severity with the first recognition during pregnancy. Established risk factors for gestational diabetes mellitus (GDM) are maternal age, obesity, family history of diabetes, etc. Vitamin D, parathyroid hormone (PTH), and various other hormones are known for their function in maintaining calcium and phosphorous homeostatic. Furthermore, Vitamin D, PTH serum ionized calcium, and alkaline phosphatase (ALP) have been reported to be altered with glucose homeostasis. The present study compares the bone markers in pregnant women with and without gestational diabetes.

MATERIALS AND METHODS

This cross-sectional study was conducted at outpatient antenatal check-up clinic and outpatient diabetic clinics at J. N. Medical College and Hospital, Aligarh. One hundred pregnant females, of which fifty with GDM and fifty without GDM, were included in the study from January 2014 to November 2015. Detailed history, physical examination, and anthropometric measurement were done. Bone turnover markers in the form of Vitamin D, parathyroid hormone, serum ionized calcium, and serum ALP were measured in pregnant women who had gestational diabetes which was compared with normal pregnant women.

RESULTS

In our study, the mean age of participate of GDM group was 28.2 ± 3 years, while the mean age group in non-GDM group was 25.44 ± 2.78 years. Ionized calcium in GDM was found to be 4.606 ± 0.354 mEq/L, while in non-GDM, it was 4.548 ± 0.384 mEq/L, P = 0.430. Vitamin D came out to be 21.80 ± 9.48 ng/ml, while it was 32.346 ± 8.37 ng/ml in non-GDM group. Serum PTH in GDM group was 71.436 ± 36.189 pg/ml and 37.168 ± 8.128 pg/ml in nondiabetic gestational group. Serum ALP in GDM group was 9.1 ± 4.56 KA U/dl and 6.98 ± 2.2 KA U/dl in nondiabetic gestational group, P - 0.0038. In GDM group, there was a significant negative linear correlation between PTH and 25-hydroxyvitamin D with research correlation coefficient r = -0.9073, P = 0; there was a significant positive linear correlation coefficient between PTH and ALP with Persian correlation coefficient r = 0.6597, P = 0; there was no statistically significant correlation between PTH and ionized calcium r = 0.1416, P = 0.3267.

CONCLUSION

All GDM subjects should ideally be screened for serum calcium, vitamin D, PTH, ALP. If found impaired should immediately be corrected in order to prevent its adverse effects on maternal and fetal outcome. Vitamin D supplementation should ideally be initiated in all GDM females even if the above parameters are not investigated in Indian setup.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Primary hyperparathyroidism in pregnancy

Primary hyperparathyroidism (PHPT) is one of the most common endocrine disorders in the general population but is rarely diagnosed during pregnancy. Symptoms of gestational PHPT may be unrecognized, or masked by physiological changes in calcium homeostasis associated with pregnancy. Gestational PHPT may have severe consequences for both mother and fetus. However, nowadays, gestational PHPT is usually diagnosed in earlier stages and milder forms, with low complication rates. Treatment should be individually tailored according to gestational age, the severity of hypercalcemia, and the risk-benefit balance. The conservative approach is preferred in mild forms, whereas surgery, usually performed during the second trimester, is reserved for symptomatic hypercalcemic PHPT. Given the young age of the patients, genetic causes should be considered.

Differential expression of calcium transport genes caused by COMT inhibition in the duodenum, kidney and placenta of pregnant mice

Preeclampsia is a pregnancy-specific disease characterized by concurrent development of hypertension, proteinuria, and oxidative stress in the placenta. Preeclampsia-like genetic models were also developed by modification of preeclampsia-related genes, such as catechol-O-methyltranferase (COMT). In this study, we induced COMT inhibition in mice during pregnancy in order to reproduce physiological conditions associated with preeclampsia. Expression of the gene known as hypoxia biomarker, HIF-1α, was highly induced in the placenta of this model. The over-expression of HIF-1α demonstrates that our experimental conditions were similar to those of preeclampsia. We measured the expression of several calcium transport genes (CTGs; TRPV5, TRPV6, PMCA1 and CaBP-9k) in the placenta, duodenum and kidney after COMT inhibition on gestation day 17.5 (GD 17.5). In addition, we evaluated the calcium transporters in the kidney, duodenum of non-pregnant female mice. Placental TRPV5, TRPV6 and PMCA1 expressions were down-regulated by COMT inhibitor (ro41-0960). In addition, the reduced PMCA1 expression in the placenta was reversed by calcium supplementation. Duodenal expressions of TRPV5, TRPV6, and PMCA1 were decreased in COMT-inhibited mice, and recovered slightly after calcium supplementation. Renal expression of TRPV5, TRPV6, and PMCA1 was also decreased by COMT inhibition, while it was reversed by calcium supplementation to the level of control. Duodenal- and renal calcium transporting genes, TRPV5, TPRV6, PMCA1 and CaBP-9k, were down-regulated by COMT treatment in female mice. Taken together, these results indicate that physiological changes observed in COMT inhibition were similar to symptoms of preeclampsia, which may be related to disturbance of calcium metabolism during pregnancy.

Serum 25-hydroxyvitamin D, calcium, and calcium-regulating hormones in preeclamptics and controls during first day postpartum

The evidence for a link between vitamin D and preeclampsia is conflicting. There is a paucity of studies reporting simultaneous 25-hydroxyvitamin D (inactive form) and 1,25-dihydroxyvitamin D (biologically active form). We investigated if levels of serum 25-hydroxyvitamin D, calcium-regulating hormones (1,25-dihydroxyvitamin D, parathyroid hormone), and calcium differ significantly between preeclamptics and controls. On postpartum day one, 98 subjects (44 with preeclampsia, 54 controls) were recruited among women admitted to the postdelivery unit, and their serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, serum calcium, and serum albumin levels were prospectively measured. The majority of participants (70%) had serum 25-hydroxyvitamin D level<20 ng/mL; 53% had <15 ng/mL. Mean serum 25-hydroxyvitamin D level was similar between cases and controls (p=0.50). Mean total serum calcium adjusted for albumin and magnesium was similar between cases and controls (p=0.78). Mean serum 1,25-dihydroxyvitamin D and parathyroid hormone levels were normal, and there were no differences between cases and controls. The only significant differences found between preeclamptic cases and controls were mean body mass index, parity, and season of blood draw. Vitamin D levels did not differ among preeclamptic cases and controls.

Gestational diabetes mellitus upregulates vitamin D receptor in extravillous trophoblasts and fetoplacental endothelial cells

OBJECTIVE

Gestational diabetes mellitus (GDM) is often accompanied by low maternal vitamin D, that is, calcitriol (1,25[OH]2 vitamin D3), levels. Here, we tested the hypothesis that the placental vitamin D receptor (VDR) is regulated by calcitriol and altered in GDM with distinct changes in different placental cell types. Specifically, we aimed to localize VDR in human term placentas from normal and GDM pregnancies, to quantify its cellular expression and to study in vitro its regulation by its physiological agonist calcitriol.

STUDY DESIGN

Placental tissue slides of 80 patients (40 with GDM/40 controls) were double stained for VDR and human leukocyte antigen G to identify extravillous trophoblasts (EVTs). Staining intensity was semiquantified. Quantitative real time-polymerase chain reaction and Western blotting measured VDR messenger RNA (mRNA) and protein in decidual tissue. The trophoblast cell line BeWo was used to study in vitro VDR regulation by calcitriol (0.01, 0.1, and 1 nmol/mL).

RESULTS

Vitamin D receptor protein and mRNA levels are upregulated (P < .05) in EVT (1.8-fold) as well as in placental endothelium (5.8-fold) of patients with GDM. Expression of VDR is regulated by calcitriol in a bimodal manner: high doses (0.1 and 1 nmol/mL) caused downregulation, whereas the low dose (0.01 nmol/mL) resulted in VDR upregulation.

CONCLUSION

Vitamin D receptor is upregulated in EVT and endothelium of GDM placentas. This could be due to low maternal vitamin D levels in patients with GDM because in vitro low calcitriol doses upregulate VDR in trophoblast cells.

The Vitamin D Antenatal Asthma Reduction Trial (VDAART): rationale, design, and methods of a randomized, controlled trial of vitamin D supplementation in pregnancy for the primary prevention of asthma and allergies in children

There is intense interest in the role of vitamin D in the development of asthma and allergies. However, studies differ on whether a higher vitamin D intake or status in pregnancy or at birth is protective against asthma and allergies. To address this uncertainty, the Vitamin D Antenatal Asthma Reduction Trial (VDAART) was developed. VDAART is a randomized, double-blind, placebo-controlled trial of vitamin D supplementation in pregnant women to determine whether prenatal supplementation can prevent the development of asthma and allergies in women's offspring. A secondary aim is to determine whether vitamin D supplementation can prevent the development of pregnancy complications, such as preeclampsia, preterm birth, and gestational diabetes. Women were randomized to the treatment arm of 4000IU/day of vitamin D3 plus a daily multivitamin that contained 400IU of vitamin D3 or the placebo arm of placebo plus a multivitamin that contained 400IU daily of vitamin D3. Women who were between the gestational ages of 10 and 18 weeks were randomized from three clinical centers across the United States - Boston Medical Center, Washington University in St. Louis, and Kaiser Permanente Southern California Region (San Diego, CA). Supplementation took place throughout pregnancy. Monthly monitoring of urinary calcium to creatinine ratio was performed in addition to medical record review for adverse events. Offspring are being evaluated quarterly through questionnaires and yearly during in-person visits until the 3rd birthday of the child. Ancillary studies will investigate neonatal T-regulatory cell function, maternal vaginal flora, and maternal and child intestinal flora.

Primary hyperparathyroidism in pregnancy

Primary hyperparathyroidism (PHPT) is rarely diagnosed during pregnancy but is associated with significant maternal and fetal morbidity and mortality. Information on appropriate management is limited. We reviewed the medical literature through December 2012 for key articles on PHPT during pregnancy, focusing on large series. Clinical knowledge in this area is restricted to isolated case reports and a few retrospective studies. Diagnosis can be difficult, owing to the non-specific nature of signs and symptoms of hypercalcemia during pregnancy. Pregnant women with a calcium level over 2.85 mmol/L (11.4 mg/dL) and prior pregnancy loss are at a particularly high risk of maternal complications (hypercalcemic crisis, nephrolithiasis, pancreatitis, etc.) and fetal loss. Around one-half of neonates born to mothers with untreated PHPT have hypocalcemia and tetany. Algorithms proposed for the management of the pregnant woman with PHPT are not evidence based, reflecting the paucity of data. Treatment should thus be individually tailored. Gestational age and the severity of hypercalcemia should be taken into account when assessing the risk-benefit balance of a conservative approach (hyperhydration and vitamin D supplementation) versus parathyroid surgery. Current evidence supports parathyroidectomy as the main treatment, performed preferably during the second trimester, when the serum calcium is above 2.75 mmol/L (11 mg/dL). In the patients with mild forms of PHPT, which are nowadays the most frequent, a conservative management is generally preferred.

Change of genes in calcium transport channels caused by hypoxic stress in the placenta, duodenum, and kidney of pregnant rats

Preeclampsia is a pregnancy-specific disease characterized by concurrent development of hypertension, proteinuria, and oxidative stress in the placenta. In this study, we induced hypoxic stress in rats during pregnancy to reproduce physiological conditions associated with preeclampsia. The maternal weight of hypoxic pregnant rats was lower than that of normoxic animals. The level of calcium ions were also increased in urine collected from the hypoxic animals. In contrast, urinary concentrations of sodium, chloride, and potassium ions declined in hypoxic rats, and developed to proteinuria. The expression of genes known as two biomarkers, sFLT1 (for preeclampsia) and HIF-1alpha (for hypoxia), were highly induced in the placenta, duodenum, and kidney by hypoxic stress. The overexpression of sFLT1 and HIF-1alpha demonstrated that our experimental conditions closely mimicked ones that are associated with preeclampsia. In the present study, we measured the expression of calcium transporters (TRPV5, TRPV6, PMCA1, NCKX3, NCX1, and CaBP-9k) in the placenta, duodenum, and kidney under hypoxic conditions on Gestational Day 19.5 in rats. Placental TRPV5, TRPV6, and PMCA1 expression was up-regulated in the hypoxic rats, whereas the levels of NCX1 and CaBP-9k were unchanged. In addition, NCKX3 expression was increased in the placenta of hypoxic rats. Duodenal expression of CaBP-9k, TRPV5, TRPV 6, and PMCA1 was decreased in the hypoxic rats, whereas levels of NCXs were not altered. Renal expression of NCKX3 and TRPV6 was increased, whereas NCX1 was decreased in the hypoxic rats compared to the normoxic controls. Taken together, these results indicate that physiological changes observed in the hypoxic rats were similar to ones associated with preeclampsia. Expression of calcium transport genes in the placenta, duodenum, and kidney perturbed by hypoxic stress during pregnancy may cause calcium loss in the urine, and thereby induce calcium-deficient characteristics of preeclampsia.

Vitamin D in the maternal-fetal-neonatal interface: clinical implications and requirements for supplementation

Identification of the current evidence regarding the pathophysiological and clinical facets of vitamin D in the maternal-fetal-neonatal interface is of value because of the significance of the vitamin D endocrine system in human health and high prevalence of vitamin D deficiency in mothers and their infants. Although many questions have still not been answered by the existing literature, we found evidence that: (i) during pregnancy vitamin D participates in fetal skeletal mineralization and growth, (ii) neonatal vitamin D levels are dependent on the maternal vitamin D status at delivery, (iii) a vitamin D sufficient status at birth may decrease the risk for the development of asthma and type 1 diabetes mellitus in later life, (iv) recommendations for maintaining serum 25-hydroxyvitamin D [25(OH)D] levels ≥32 ng/mL to avoid secondary hyperparathyroidism in adults have not been applied to mothers and their infants, (v) American Academy of Pediatrics recommended supplementation of 400 IU of vitamin D per day is sufficient only for infants who are born with normal vitamin D levels and (vii) supplementation of lactating mothers with high doses of vitamin D (4000 IU/d) allows the achievement of optimal 25(OH)D concentrations (>32 ng/mL) in the maternal and infant serum without any risk of hypervitaminosis D in the mother. We believe that inconsistency in the recognition of sufficient levels of vitamin D in mothers and their infants affects the identification of adequate doses for vitamin D supplementation during pregnancy, lactation and infancy.

Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period

BACKGROUND

Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized.

OBJECTIVE

The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation.

DESIGN

Stable calcium isotopes were given to 46 women at pre- or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3-10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)₂D], parathyroid hormone, and calcium intake were evaluated.

RESULTS

At trimester 3, inverse associations between 1,25(OH)₂D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P ≤ 0.002) and between VO+ and African ethnicity (P ≤ 0.004) in the whole group and within the Baltimore and Brazil cohorts.

CONCLUSIONS

Elevated 1,25(OH)₂D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period.

Vitamin D insufficiency is prevalent and vitamin D is inversely associated with parathyroid hormone and calcitriol in pregnant adolescents

Few large studies have assessed changes in calcitropic hormones and maternal 25-hydroxyvitamin D (25(OH)D) status across pregnancy, and how this may impact maternal bone turnover and neonatal hormone status. We aimed to identify determinants of 25(OH)D, parathyroid hormone (PTH), and calcitriol across pregnancy in a longitudinal study of 168 pregnant adolescents (≤18 years of age). Maternal 25(OH)D, PTH, and calcitriol were assessed at mid-gestation (∼26 weeks), delivery, and in cord blood. Data were related to measures of maternal anthropometrics, dietary intake, physical activity, and bone turnover markers. Approximately 50% of teens and their infants had serum 25(OH)D ≤ 20 ng/mL; 25(OH)D was lower in African Americans versus whites (p < 0.001). PTH increased across gestation (p < 0.001). Elevated PTH (≥60 pg/mL) was detected in 25% of adolescents at delivery, and was associated with increased concentrations of serum N-telopeptide (NTX) (p = 0.028). PTH and calcitriol did not significantly differ across the range of Ca intake consumed (257-3220 mg/d). In the group as a whole, PTH was inversely associated with 25(OH)D in maternal circulation at mid-gestation (p = 0.023) and at delivery (p = 0.019). However, when the cohort was partitioned by 25(OH)D status, this relationship was only present in those with 25(OH)D ≤ 20 ng/mL, suggestive of a threshold below which 25(OH)D impacts PTH during pregnancy. Mid-gestation 25(OH)D was inversely associated with calcitriol at delivery (p = 0.023), irrespective of Ca intake. Neonatal PTH and calcitriol were significantly lower than (p < 0.001), but unrelated to maternal concentrations. These findings indicate that maternal 25(OH)D status plays a role in calcitropic hormone regulation in pregnant adolescents.

Vitamin D in pregnancy and lactation in humans

Concerns exist about the adequacy of vitamin D in pregnant and lactating women. This review assesses the evidence that maternal vitamin D status influences maternal, fetal, and breast-fed infant bone health; maternal adverse outcomes (preeclampsia, gestational diabetes, obstructed labor, and infectious disease); fetal adverse outcomes (growth, gestational age, and developmental programming); and infant adverse outcomes. The evidence for all of these outcomes is contradictory (except for maternal infectious disease) and lacking causality; thus, it is inconclusive. The 2011 Dietary Reference Intakes for vitamin D and their implications for assessing vitamin D status are discussed. An estimated 5% to 29% of American pregnant women may have inadequate vitamin D status, with the higher prevalence in African Americans. Little is known about the prevalence of inadequacy in American lactating women. Research needs are also identified, especially the need for rigorous and well-designed randomized clinical trials to determine the role of vitamin D in nonbone health outcomes in pregnancy and lactation.

The relationship between PTH and 25-hydroxy vitamin D early in pregnancy

OBJECTIVE

Measure serum PTH and 25(OH)D in a cross-sectional sample of pregnant women at 11th through 13th weeks' gestation to examine vitamin D status and consider implications.

DESIGN

Observational: we retrieved residual sera stored at -20 °C after routine first trimester Down's syndrome screening, distributed over 12 months.

PATIENTS

430 African American women and 586 Caucasian women.

MEASUREMENTS

PTH and 25-hydroxy vitamin D [25(OH)D] immunoassays.

RESULTS

PTH medians were: 1·33 pmol/l (African American women); 1·20 pmol/l (Caucasian women) (t = 0·43, P = 0·7). Concentrations were highest in winter and decreased significantly in spring, fall, and summer. There was a direct PTH/weight relationship in Caucasian (t = 3·12, P < 0·002), but not African American women (t = 1·34, P = 0·18). Median 25(OH)D concentrations were 47·5 nmol/l (African American women) and 65 nmol/l (Caucasian women) (t = 13·7, P < 0·001). Concentrations were lowest in winter and rose significantly in spring, fall, and summer. Reciprocal 25(OH)D/weight relationships existed for both racial groups (t =-4·31 P < 0·001; t = 4·54, P < 0·001, respectively). Among 68 Caucasian women who smoked, median PTH and 25(OH)D concentrations were somewhat lower (P = ns). In separate regression models with PTH and 25(OH)D [dependent variables] and season, weight and smoking [independent variables], the only qualifying interactive term was in the Caucasian PTH model (season*1/weight). A regression model applied to adjusted scatter plots of PTH vs 25(OH)D indicated a weak relationship.

CONCLUSIONS

The PTH/25(OH)D relationship is weaker during early pregnancy than in non-pregnant adults, making it unreliable for estimating vitamin D sufficiency. A suitable reference point for sufficiency might be the maternal 25(OH)D level considered sufficient for adequate transfer to neonates.

Primary hyperparathyroidism in pregnancy-a rare cause of life-threatening hypercalcemia: case report and literature review

Objective. To report a case of primary hyperparathyroidism in a pregnant patient, report the obstetric and neonatal outcomes, and review the relevant literature. Results. A 29-year-old primigravida was successfully treated for PHP with minimally invasive resection of a parathyroid adenoma in the second trimester of pregnancy. A healthy baby girl was delivered at 37-week gestation with an unremarkable neonatal course. To the best of our knowledge, this is the second case report in the literature utilizing intraoperative PTH during a parathyroidectomy in a pregnant woman. Conclusions. Primary hyperparathyroidism is a rare life-threatening condition that can present during pregnancy. The diagnosis can be difficult to establish during pregnancy, given the nonspecific symptoms related to hypercalcemia. However, a better understanding of the condition, improved diagnostic studies, and well-organized multidisciplinary management decisions can significantly reduce the morbidity and mortality associated with the disease during pregnancy. This case report is presented to highlight the value of early diagnosis and appropriate management of PHP during pregnancy.

Vitamin D status in pregnant Indian women across trimesters and different seasons and its correlation with neonatal serum 25-hydroxyvitamin D levels

The present cross-sectional study was conducted to determine the vitamin D status of pregnant Indian women and their breast-fed infants. Subjects were recruited from the Department of Obstetrics, Armed Forces Clinic and Army Hospital (Research and Referral), Delhi. A total of 541 apparently healthy women with uncomplicated, single, intra-uterine gestation reporting in any trimester were consecutively recruited. Of these 541 women, 299 (first trimester, ninety-seven; second trimester, 125; third trimester, seventy-seven) were recruited in summer (April–October) and 242 (first trimester, fifty-nine, second trimester, ninety-three; third trimester, ninety) were recruited in winter (November–March) to study seasonal variations in vitamin D status. Clinical, dietary, biochemical and hormonal evaluations for the Ca–vitamin D–parathormone axis were performed. A subset of 342 mother–infant pairs was re-evaluated 6 weeks postpartum. Mean serum 25-hydroxyvitamin D (25(OH)D) of pregnant women was 23·2 (sd 12·2) nmol/l. Hypovitaminosis D (25(OH)D < 50 nmol/l) was observed in 96·3 % of the subjects. Serum 25(OH)D levels were significantly lower in winter in the second and third trimesters, while serum intact parathormone (iPTH) and alkaline phosphatase levels were significantly higher in winter in all three trimesters. A significant negative correlation was found between serum 25(OH)D and iPTH in mothers (r − 0·367, P = 0·0001) and infants (r − 0·56, P = 0·0001). A strong positive correlation was observed between 25(OH)D levels of mother–infant pairs (r 0·779, P = 0·0001). A high prevalence of hypovitaminosis D was observed in pregnancy, lactation and infancy with no significant inter-trimester differences in serum 25(OH)D levels.

The Role of Calcium Correction during Normal Pregnancy at Third Trimester in Mosul

OBJECTIVES

To assess calcium status in healthy pregnant women during limited sun exposure time in winter, and to demonstrate the possible effect of serum albumin alterations on serum total calcium level and the role of albumin adjusted calcium concentration.

METHODS

Subjects enrolled in the study included 160 apparently healthy women divided equally into four groups (I - IV), group I was considered as the control group, composed of non-pregnant women. Groups II-IV were composed of pregnant women in the first, second and third trimesters respectively. Semiquantitative urine protein determination and measurement of serum total calcium, ionized calcium, albumin, phosphorous and creatinine with calculation of corrected calcium were performed in all groups. The results were statistically evaluated by standard statistical methods.

RESULTS

There was no significant difference in serum ionized calcium, corrected calcium and phosphorous during pregnancy. However, there was a significant reduction of serum total calcium, albumin and creatinine in pregnant women at second and third trimesters. In each group, a significant positive correlation was observed between total calcium with corrected and ionized calcium.

CONCLUSION

In healthy pregnant women even during limited sun exposure time in winter, there was no need for calcium supplementation in spite of the continuous and progressive reduction of serum measured total calcium during the second and third trimesters due to dilutional hypoalbuminemia. During pregnancy, measured calcium is parallel to both corrected and ionized calcium and since there was no significant difference between measured and corrected calcium, therefore, measured calcium is a useful test in assessing calcium status and suggests the need to establish a reference range for pregnant women.

Calcium in midpregnancy

OBJECTIVE

To establish reference value for serum calcium concentration and urinary calcium excretion during mid pregnancy and to find out variation of calcium intake in pregnant women.

MATERIALS AND METHODS

This was a cross sectional study conducted in antenatal clinic of department of Obstetrics and Gynaecology. A total of 543 pregnant women with pregnancy period of second trimester were enrolled for the study. Eligible healthy, vegetarian primigravid women provided serum and 24 h urinary samples for determination of serum calcium and urinary calcium excretion. Dietary intake calculated by 3-day recall method. Variation of calcium intake according to various demographic characteristics was noted.

RESULTS

Statistical analysis done with SPSS software. The mean total serum calcium and 24 h urinary calcium and dietary intake of calcium were 8.1+/-1.5 mg/dl (5.1-11.9), 129.56+/-67.08 mg (40.5-400) and 324.37+/-199.47 mg/day (85.71-910.71) respectively. The 95th percentiles for serum calcium were 10.56 mg/dl and urinary calcium excretion was 280.70 mg/24 h. Educational level, monthly income and height were positive correlated with calcium intake.

CONCLUSION

This preliminary study defines the first standard value for calcium status in pregnant second trimester females of northern India. Calcium intake in pregnant females is affected by various demographic characteristics. There is need to change dietary pattern by improving education and socio-economic level.

Inherited disorders of calcium homeostasis

In mammals a complicated homeostatic mechanism has evolved to maintain near consistency of extracellular calcium ion levels. The homeostatic mechanism involves several hormones, which comprise among others, parathyroid hormone and vitamin D. The recent resurge in vitamin D deficiency, as a global health issue, has increased interest in the hormone. In addition to vitamin D deficiency, other causes of rickets are calcium deficiency and inherited disorders of vitamin D and phosphorus metabolism. Vitamin D-resistant syndromes are caused by hereditary defects in metabolic activation of the hormone or by mutations in the vitamin D receptor, which binds the hormone with high affinity and regulates the expression of genes through zinc finger mediated DNA binding and protein-protein interaction. Current interest is to correlate the type/position of mutations that result in disorders of vitamin D metabolism or in vitamin D receptor function with the variable phenotypic features and clinical presentation. The calcium sensing receptor plays a key role in calcium homeostasis. Loss of function mutations in the calcium sensing receptor can cause familial benign hypocalciuric hypercalcemia in heterozygotes and neonatal severe hyperparathyroidism when homozygous mutations occur in the calcium sensing receptor. Gain of function mutation can cause the opposite effect causing autosomal dominant hypocalcemia. Mouse models using targeted gene disruption strategies have been valuable tools to study the effect of mutations on the calcium sensing receptor or in the vitamin D activation pathway. Dysfunctional calcium sensing receptors with function altering mutations may be responsive to treatment with allosteric modulators of the calcium sensing receptor. Vitamin D analogs which induce unusual structural conformations on the vitamin D receptor may have a variety of therapeutic indications. This review summarises recent advances in knowledge of the molecular pathology of inherited disorders of calcium homeostasis.

Hyperparathyroid crisis: use of bisphosphonates as a bridge to parathyroidectomy

BACKGROUND

Hyperparathyroid crisis is an uncommon, potentially lethal condition for which emergent parathyroidectomy has been advocated.

STUDY DESIGN

The manifestations of hyperparathyroid crisis and outcomes of bisphosphonate-based therapy and delayed parathyroidectomy were determined and compared with cases from a review of the literature. Laboratory indices and gland weights were compared with those from patients with primary hyperparathyroidism without crisis.

RESULTS

Of the 292 patients operated on for hyperparathyroidism, 8 (2.8%) had hyperparathyroid crisis, consistent with rates of 1.6% to 6% reported in the literature. Hyperparathyroid crisis was manifested by vomiting, nausea, or both (n=6); abdominal pain (n=3); mental status changes (n=3); pancreatitis (n=2); bone pain, osteolytic lesions, or both (n=2); electrocardiogram changes (n=1); and an acute conversion disorder (n=1). Isotonic sodium chloride and furosemide, in combination with a bisphosphonate drug in 7 of 8 patients, resulted in a calcium decline from 16.2+/-1.6 mg/dL to 11.8+/-1.6 mg/dL, with resolution of electrocardiogram and mental status changes, and pancreatitis before resection of an adenoma (n=7) or carcinoma (n=1). Patients with hyperparathyroid crisis had higher parathyroid hormone levels (691.7 +/-662.4 pg/mL versus 172.6 +/-147.5 pg/mL; p=0.062), larger tumor weights (7.5 +/-8.4 g versus 1.6 +/-2.1 g; p=0.085), and lower postoperative calcium levels (7.3 +/-1.6 mg/dL versus 8.7+/-0.9 mg/dL; p=0.035) than patients without crisis. Four (50%) of the 8 tumors were found in ectopic locations. There was no mortality from hyperparathyroid crisis, compared with a 7% mortality rate for cases reported in the literature since 1978.

CONCLUSIONS

Rehydration, calciuresis, and bisphosphonate therapy are effective in correcting life-threatening manifestations of hyperparathyroid crisis, providing an effective bridge to parathyroidectomy.

Vitamin D insufficiency is common in Indian mothers but is not associated with gestational diabetes or variation in newborn size

BACKGROUND/OBJECTIVES

Vitamin D is required for bone growth and normal insulin secretion. Maternal hypovitaminosis D may impair fetal growth and increase the risk of gestational diabetes. We have related maternal vitamin D status in pregnancy to maternal and newborn glucose and insulin concentrations, and newborn size, in a South Indian population.

SUBJECTS/METHODS

Serum 25 hydroxy vitamin D (25(OH)D) concentrations, glucose tolerance, and plasma insulin, proinsulin and 32-33 split proinsulin concentrations were measured at 30 weeks gestation in 559 women who delivered at the Holdsworth Memorial Hospital, Mysore. The babies' anthropometry and cord plasma glucose, insulin and insulin precursor concentrations were measured.

RESULTS

In total 66% of women had hypovitaminosis D (25(OH)D concentrations <50 nmol l(-1)) and 31% were below 28 nmol l(-1). There was seasonal variation in 25(OH)D concentrations (P<0.0001). There was no association between maternal 25(OH)D and gestational diabetes (incidence 7% in women with and without hypovitaminosis D). Maternal 25(OH)D concentrations were unrelated to newborn anthropometry or cord plasma variables. In mothers with hypovitaminosis D, higher 25(OH)D concentrations were associated with lower 30-min glucose concentrations (P=0.03) and higher fasting proinsulin concentrations (P=0.04).

CONCLUSIONS

Hypovitaminosis D at 30 weeks gestation is common in Mysore mothers. It is not associated with an increased risk of gestational diabetes, impaired fetal growth or altered neonatal cord plasma insulin secretory profile.

Changes in calcium, 25(OH) vitamin D3 and other biochemical factors during pregnancy

INTRODUCTION AND AIMS

Calcium and vitamin D play major roles in calcium homeostasis and skeletal development, especially during pregnancy. This study was conducted to determine changes in calcium, 25 hydroxy [25(OH)] vitamin D3 and other biochemical factors (PTH, osteocalcin, alkaline phosphatase, magnesium, phosphorus) related to calcium homeostasis and bone turnover during pregnancy and compare the values to those of non-pregnant women.

MATERIALS AND METHODS

In a cohort study, 48 pregnant women, in their first trimester of pregnancy (12+/-2.7 weeks), from 5 prenatal care centers, and 47 non-pregnant women randomly selected from the Tehran Lipid and Glucose Study (TLGS) population were enrolled. These pregnant women were followed in their second (26+/-1.9 weeks) and third trimesters (37+/-3.2 weeks) of pregnancy. Samples were drawn from June 2002 to March 2003. Including criteria were healthy women with no background of disease. Women using photo protection and calcium and vitamin D supplementation were excluded. A questionnaire was used to obtain demographic information for both groups. Venous blood samples were taken after 12-14 h of overnight fasting to measure serum calcium, phosphorus, magnesium, alkaline phosphatase, PTH, 25 (OH) vitamin D3 and serum osteocalcin levels. The repeated measures analysis of variance and t-test were used for statistical analysis. Data were matched for age and weight in both the case (in the first trimester) and control groups.

RESULTS

Significant differences were found in the mean serum levels of osteocalcin and alkaline phosphatase between the three trimesters of pregnancy (p< 0.001). Osteocalcin was significantly higher in the first trimester as compared to second and third trimesters of pregnancy. Alkaline phosphatase was significantly lower in the first trimester as compared to the second and third trimesters of pregnancy and their controls. There was also a significant difference in osteocalcin in the second and third trimesters and alkaline phosphatase in the first and third trimesters of pregnancy in comparison to the control group. The mean values of osteocalcin were 12.7+/-8.5, 8.1+/-6.9, 5.6+/-5.0 and 13.9+/-7.9 ng/ml, respectively, and mean values for alkaline phosphatase were 115+/-38, 125+/-37, 174+/-61 and 134+/-35.0 Iu/l, respectively. In the first trimester, alkaline phosphatase was lower and osteocalcin was higher than in the second and third trimesters. In the first trimester of pregnancy, 20 and 40% of women had 25(OH) vitamin D3 < 10 and < 20 ng/ml, respectively, and 19% of women had serum calcium levels < 8.6 mg/dl.

CONCLUSION

60% of women in the first trimester, 48% in the second and 47% in the third trimester had either severe or moderate vitamin D deficiency. It is recommended that the importance of calcium supplements with vitamin D in pregnant women be stressed for these individuals.

Adapting to the transition between gestation and lactation: differences between rat, human and dairy cow

Adequate blood calcium concentrations are vital for the normal function of mammals. Mechanisms for maintaining normal blood calcium function adequately most of the time; however, occasionally they fail and calcium homeostasis is compromised. Milk fever or periparturient hypocalcemia in dairy cattle is a well-documented example of a breakdown in the mechanisms of calcium homeostasis. This disease occurs at the time of parturition and is unique to adult dairy animals. The disease results from the inability of animals to cope with the sudden demand for calcium in support of colostrum formation. Animals developing the disease become hypocalcemic and require intravenous calcium to survive. The precise metabolic disorder(s) responsible for the onset of milk fever is still being debated. This report will highlight some of the current concepts related to the causes and prevention of milk fever in dairy cattle, as well as contrasting differences in calcium demands that exist between dairy cattle, humans and rats at the onset of lactation.

Accelerated Mammary Gland Development during Pregnancy and Delayed Postlactational Involution in Vitamin D3 Receptor Null Mice

The vitamin D receptor (VDR) is present in mammary gland, and VDR ablation is associated with accelerated glandular development during puberty. VDR is a nuclear receptor whose ligand, 1,25-dihydroxyvitamin D [1,25-(OH)2D] is generated after metabolic activation of vitamin D by specific vitamin D hydroxylases. In these studies, we demonstrate that both the VDR and the vitamin D 1-α hydroxylase (CYP27B1), which produces 1,25-(OH)2D are present in mammary gland and dynamically regulated during pregnancy, lactation, and involution. Furthermore, we show that mice lacking VDR exhibit accelerated lobuloalveolar development and premature casein expression during pregnancy and delayed postlactational involution compared with mice with functional VDR. The delay in mammary gland regression after weaning of VDR knockout mice is associated with impaired apoptosis as demonstrated by reductions in terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling staining, caspase-3 activation and Bax induction. Under the conditions used in this study, VDR ablation was not associated with hypocalcemia, suggesting that altered mammary gland development in the absence of the VDR is not related to disturbances in calcium homeostasis. Furthermore, in the setting of normocalcemia, VDR ablation does not affect milk protein or calcium content. These studies suggest that the VDR contributes to mammary cell turnover during the reproductive cycle, and its effects may be mediated via both endocrine and autocrine signaling pathways. Unlike many mammary regulatory factors that exert transient, stage-specific effects, VDR signaling impacts on mammary gland biology during all phases of the reproductive cycle.

Aldosterone potentiates 1,25-dihydroxyvitamin D3 action in renal thick ascending limb via a nongenomic, ERK-dependent pathway

Recently, we demonstrated that aldosterone inhibits HCO3- absorption in the rat medullary thick ascending limb (MTAL) via a nongenomic pathway blocked by inhibitors of extracellular signal-regulated kinase (ERK) activation. Here we examined the effects on the MTAL of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], which regulates cell functions through nongenomic mechanisms in nonrenal systems. Addition of 1 nM 1,25(OH)2D3 to the bath decreased HCO3- absorption by 24%, from 15.0 +/- 0.3 to 11.4 +/- 0.5 pmol. min-1. mm-1 (P < 0.001). This inhibition was maximal within 60 min and was eliminated by pretreatment with actinomycin D, cycloheximide, or inhibitors of protein kinase C. In MTAL bathed with 1 nM aldosterone [added 15-20 min before 1,25(OH)2D3], the absolute (5.6 +/- 0.3 vs. 3.6 +/- 0.3 pmol. min-1. mm-1) and fractional (49 +/- 2 vs. 24 +/- 2%) decreases in HCO3- absorption induced by 1,25(OH)2D3 were significantly greater than those in the absence of aldosterone (P < 0.05). The effect of aldosterone to potentiate inhibition by 1,25(OH)2D3 was not affected by spironolactone but was eliminated by the MAPK kinase/ERK inhibitor U-0126. U-0126 did not affect inhibition of HCO3- absorption by 1,25(OH)2D3 alone. Aldosterone induced rapid activation of ERK via a transcription-independent pathway. We conclude that 1) 1,25(OH)2D3 inhibits HCO3- absorption in the MTAL via a genomic pathway involving protein kinase C, which may contribute to 1,25(OH)2D3-induced regulation of urinary net acid and/or Ca2+ excretion and 2) aldosterone potentiates inhibition by 1,25(OH)2D3 through an ERK-dependent, nongenomic pathway. These results identify a novel regulatory interaction whereby aldosterone acts via nongenomic mechanisms to enhance the genomic response to 1,25(OH)2D3. Aldosterone may influence a broad range of biological processes, including epithelial transport, by modifying the response of target tissues to 1,25(OH)2D3 stimulation.

Bone in the pregnant mother and newborn at birth

BACKGROUND

Changes in maternal bone during pregnancy may affect fetal bone mineralization.

ISSUES

The biphasic changes in maternal bone histology (temporary loss of cancellous bone in early pregnancy restored by term gestation) are consistent with corresponding blood biochemistry changes; increased bone resorption markers in the first trimester, while bone formation markers increased in the last trimester. Postpartum bone mineral density (BMD) by DEXA is increased at cortical bone and decreased at trabecular bone sites compared with prepregnancy values. The mean reduction of spine BMD is 3.5% from prepregnancy to immediate postpartum. Neonatal bone mineral content (BMC) is different by season of birth, low weight relative to gestation, and having a diabetic mother. Lower total body BMC and high bone resorption marker in winter vs. summer-born newborns was related to low vitamin D, indicating alterations of fetal bone metabolism by maternal D deficiency. Lower BMC and decreased bone formation marker in infants born small for gestational age than those born appropriate for gestation may relate to reduced transplacental mineral transfer. Low BMC in infants of diabetic mother was correlated inversely with poor control of maternal diabetes during early pregnancy.

CONCLUSIONS

During pregnancy, maternal bone mineral metabolism are changed, and influences on fetal bone mineralization occur in utero.

Release of lead from bone in pregnancy and lactation

Concentrations and isotope ratios of lead in blood, urine, 24-h duplicate diets, and hand wipes were measured for 12 women from the second trimester of pregnancy until at least 8 months after delivery. Six bottle fed and six breast fed their infants. One bottle feeder fell pregnant for a second time, as did a breast feeder, and each was followed semicontinuously for totals of 44 and 54 months, respectively. Bone resorption rather than dietary absorption controls changes in blood lead, but in pregnancy the resorption of trabecular and cortical bone are decoupled. In early pregnancy, only trabecular bone (presumably of low lead content) is resorbed, causing blood leads to fall more than expected from hemodilution alone. In late pregnancy, the sites of resorption move to cortical bone of higher lead content and blood leads rise. In bottle feeders, the cortical bone contribution ceases immediately after delivery, but any tendency for blood leads to fall may be compensated by the effect of hemoconcentration produced by the postpartum loss of plasma volume. In lactation, the whole skeleton undergoes resorption and the blood leads of nursing mothers continue to rise, reaching a maximum 6-8 months after delivery. Blood leads fall from pregnancy to pregnancy, implying that the greatest risk of lead toxicity lies with first pregnancies.

Nutritional assessment and support during pregnancy

This article thoroughly updates the authors' previous review of nutritional assessment and support during pregnancy. After briefly reviewing nutrient metabolism and requirements, the authors discuss the nutritional assessment of the pregnant woman and review the nutritional support principles in hyperemesis gravidarum and other conditions that can compromise the nutritional health of mother or fetus.