Pregnancy associated osteoporosis

Bone fragility and osteoporosis in children and young adults

Osteoporosis is a metabolic bone disorder which increases fragility fracture risk. Elderly individuals, especially postmenopausal women, are particularly susceptible to osteoporosis. Although rare, osteoporosis in children and young adults is becoming increasingly evident, highlighting the need for timely diagnosis, management and follow-up. Early-onset osteoporosis is defined as the presence of a low BMD (Z-score of ≤ -2.0 in individuals aged < 20 years; T-score of ≤ -2.5 in those aged between 20 to 50 years) accompanied by a clinically significant fracture history, or the presence of low-energy vertebral compression fractures even in the absence of osteoporosis. Affected children and young adults should undergo a thorough diagnostic workup, including collection of clinical history, radiography, biochemical investigation and possibly bone biopsy. Once secondary factors and comorbidities are excluded, genetic testing should be considered to determine the possibility of an underlying monogenic cause. Defects in genes related to type I collagen biosynthesis are the commonest contributors of primary osteoporosis, followed by loss-of-function variants in genes encoding key regulatory proteins of canonical WNT signalling (specifically LRP5 and WNT1), the actin-binding plastin-3 protein (encoded by PLS3) resulting in X-linked osteoporosis, and the more recent sphingomyelin synthase 2 (encoded by SGMS2) which is critical for signal transduction affecting sphingomyelin metabolism. Despite these discoveries, genetic causes and underlying mechanisms in early-onset osteoporosis remain largely unknown, and if no causal gene is identified, early-onset osteoporosis is deemed idiopathic. This calls for further research to unravel the molecular mechanisms driving early-onset osteoporosis that consequently will aid in patient management and individualised targeted therapy.

Pregnancy- and lactation-related osteoporosis: an important topic also for rheumatologists

<b>Objectives</b> <b>Material and methods</b> <b>Results</b> <b>Conclusions</b> <b></b> <b></b>

Clinical characteristics of pregnancy and lactation associated osteoporosis: An online survey study

Pregnancy and lactation associated osteoporosis is a rare and often severe osteoporosis presentation. Little information is available about etiology, clinical characteristics, risk factors and predictors of severity. Using an anonymized questionnaire, we defined clinical characteristics and potential risk factors for disease severity in PLO including primiparity, heparin exposure and celiac disease.

PURPOSE

Pregnancy and lactation associated osteoporosis (PLO) is a rare form of early-onset osteoporosis in which young women present with fractures, usually multiple vertebral fractures, during late pregnancy or lactation. Little information is available about etiology, clinical characteristics, risk factors and predictors of disease severity.

METHODS

PLO patients were recruited to complete an anonymized online questionnaire. Disease severity was defined as total number of fractures during or after the first pregnancy associated with a fracture(s). Analyses related disease severity to potential predictors including diseases/conditions or medication exposures.

RESULTS

177 completed surveys were received between 5/29/2018 and 1/12/2022. Average age at initial PLO fracture event was 32 ± 5 years. The majority were primiparous with singleton pregnancy and 79% fractured during lactation. Subjects reported 4.7 ± 2.7 total PLO fractures, with 48% reporting ≥ 5 fractures. Vertebral fractures, reported by 164/177 responders (93%), were the most common fracture type. Conditions and medications most commonly reported included vitamin D deficiency, amenorrhea unrelated to pregnancy, nephrolithiasis, celiac disease (CD), oral steroid use, heparin products during pregnancy and progestin only contraceptive after pregnancy. CD and heparins exposure during pregnancy were significantly related to disease severity.

CONCLUSION

This is the largest study characterizing clinical features of PLO to date. The large number of participants and broad range of clinical and fracture characteristics queried has yielded novel information on the characteristics of PLO and potential risk factors for its severity, including primiparity, exposure to heparin and CD. These findings provide important preliminary data that can help target future mechanistic investigations.

Pregnancy- and lactation-induced osteoporosis: a social-media-based survey

BACKGROUND

Pregnancy- and lactation-induced osteoporosis (PLO) presenting as spinal fractures is rare, and the spectrum of clinical presentation, risk factors and pathophysiology are incompletely understood. The aim of this study was to delineate clinical parameters, risk factors and osteoporosis-related quality of life (QOL) of women with PLO.

METHODS

Participants of a social-media (WhatsApp) PLO group and mothers of a parents' WhatsApp group (control group) were offered to fill a questionnaire, including an osteoporosis-related QOL section. The groups were compared using the independent Students t test for numerical variables, and the Chi-square test or Fisher's exact test for categorical variables.

RESULTS

Twenty-seven women with PLO and 43 in the control group (aged 36.2 ± 4.7 and 38.8 ± 4.3 years, respectively, p = 0.04) participated. Among women with PLO, more than 5 vertebrae were involved in 13 (48%), 4 vertebrae in 6 (22%), and 3 or fewer vertebrae in 8 (30%). Among the 24 women with relevant data, 21 (88%) had nontraumatic fractures; 3 (13%) women had fractures during pregnancy, and the remaining during the early postpartum period. Diagnosis was delayed for over 16 weeks for 11 (41%) women; 16 (67%) received teriparatide. Significantly lower proportions of women in the PLO group engaged in physical activity over 2 hours/week, before and during pregnancy (37 vs. 67%, p < 0.015 and 11 vs. 44%, p < 0.003, respectively). A lower proportion of the PLO than the control group reported calcium supplementation during pregnancy (7% vs. 30%, p = 0.03) and a higher proportion reported treatment with low-molecular-weight-heparin during pregnancy (p = 0.03). Eighteen (67%) of the PLO group expressed fear of fractures and 15 (56%) fear of falls, compared to none and 2%, respectively, of the control group (p < 0.00001 for both).

CONCLUSIONS

Most of the women with PLO who responded to our survey reported spinal fractures involving multiple vertebrae, delayed diagnosis, and treatment with teriparatide. Compared to a control group, they reported less physical activity and impaired QOL. For this uncommon yet severe condition, a multidisciplinary effort should be exerted for early identification and treatment, to alleviate back pain, prevent subsequent fractures and improve QOL.

Pregnancy- and Lactation-Associated Osteoporotic Vertebral Fracture: A Case Report

The report details an instance of a 29-year-old postpartum female who presented to us after six months of delivery and had symptoms of severe back pain since the sixth month of pregnancy. The pain was located in the lower thoracic and lumbar regions. It got aggravated by standing or walking and got relieved by lying down. The pain was radiating from the back to both lower limbs. On examination, forward rounding of the upper back, i.e., kyphosis, was seen, for which the patient was advised to get an X-ray, which was suggestive of severe osteopenia with wedging of L1-L4 vertebrae. For a thorough assessment, MRI was performed, which confirmed exaggerated kyphosis at L1 and L2 with mild scoliosis in the thoracolumbar region. The patient was advised to take calcium and vitamin D supplements with bisphosphonates. A monthly checkup was advised. After four months, the symptoms of the patient were partially eased. On investigation, the serum calcium and phosphorous levels were found to be within the normal range.

"Pregnancy and Lactation Associated Osteoporosis"

Pregnancy-associated osteoporosis (PAO) is a rare condition of skeletal fragility affecting women in pregnancy or the postpartum period. During normal pregnancy and lactation, substantial changes in calcium metabolism and skeletal physiology occur in order to meet the demands of the developing foetus. Whilst these adaptations are reversible and generally of no clinical consequence for the mother, a small number of women will develop osteoporosis and suffer fragility fractures. Vertebral fractures occur most commonly in PAO and are often multiple. Due to the rarity of PAO, systematic study to date has been limited. Aetiology is poorly understood, but traditional osteoporosis risk factors and genetic factors are likely to play a role. A small number of cases may be due to an underlying metabolic bone disorder or monogenic condition. Management of PAO is challenging, due both to a poor evidence base and the fact that spontaneous improvement in BMD is known to occur once pregnancy and lactation are complete. Bisphosphonates, denosumab and teriparatide have all been used in individual patients, but the data supporting their use are currently limited.

Case report: Early-onset osteoporosis in a patient carrying a novel heterozygous variant of the WNT1 gene

The WNT1 gene is crucial for bone development and homeostasis. Homozygous mutations in WNT1 cause severe bone fragility known as osteogenesis imperfecta type XV. Moreover, heterozygous WNT1 mutations have been found in adults with early-onset osteoporosis. We identified a 35 year-old Caucasian woman who experienced multiple vertebral fractures two months after her second pregnancy. There was no history of risk factors for secondary osteoporosis or family history of osteoporosis. Dual-energy X-ray absorptiometry confirmed a marked reduction of bone mineral density (BMD) at the lumbar spine (0.734 g/cm², Z-score -2.8), femoral neck (0.48 g/cm², Z-score -3.5), and total hip (0.589 g/cm², Z-score -3.0). Blood tests excluded secondary causes of bone fragility. Genetic analysis revealed a heterozygous missense mutation (p.Leu370Val) in the WNT1 gene. Varsome classified it as a variant of uncertain significance. However, the fact that the Leucine residue at position 370 is highly conserved among vertebrate species and the variant has a very low allelic frequency in the general population would exclude the possibility of a polymorphism. The patient was treated for two years with teriparatide therapy associated with calcium and vitamin D supplements. During the follow-up period she did not report further clinical fractures. After 24 months of teriparatide, BMD increased at lumbar spine (+14.6%), femoral neck (+8.3%) and total hip (+4.9%) compared to baseline. We confirm that the heterozygous WNT1 mutation could cause a variable bone fragility and low turnover osteoporosis. We suggest that teriparatide is one of the most appropriate available therapies for this case.

The Relationship Between Bone and Reproductive Hormones Beyond Estrogens and Androgens

Reproductive hormones play a crucial role in the growth and maintenance of the mammalian skeleton. Indeed, the biological significance for this hormonal regulation of skeletal homeostasis is best illustrated by common clinical reproductive disorders, such as primary ovarian insufficiency, hypothalamic amenorrhea, congenital hypogonadotropic hypogonadism, and early menopause, which contribute to the clinical burden of low bone mineral density and increased risk for fragility fracture. Emerging evidence relating to traditional reproductive hormones and the recent discovery of newer reproductive neuropeptides and hormones has deepened our understanding of the interaction between bone and the reproductive system. In this review, we provide a contemporary summary of the literature examining the relationship between bone biology and reproductive signals that extend beyond estrogens and androgens, and include kisspeptin, gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, progesterone, inhibin, activin, and relaxin. A comprehensive and up-to-date review of the recent basic and clinical research advances is essential given the prevalence of clinical reproductive disorders, the emerging roles of upstream reproductive hormones in bone physiology, as well as the urgent need to develop novel safe and effective therapies for bone fragility in a rapidly aging population.

Malleolar fracture in pregnancy and lactation-associated osteoporosis: a case report and literature review

OBJECTIVE

The incidence of fractures in pregnancy and lactation-associated osteoporosis (PLO) is very low. Some fracture cases of PLO are associated with vertebral compression fractures, while malleolar fractures in patients with PLO are rarely reported before.

CASE REPORT

A 31-year-old Han Chinese patient presented with a malleolar fracture 3 months after delivery, while she was still breastfeeding. Temporary closed reduction and plaster external fixation were performed in the emergency room. Then the patient was admitted to the orthopedic trauma ward for surgery and diagnosed as PLO by dual-energy X-ray absorptiometry (DEXA). After preoperative evaluation, the patient underwent open reduction and internal fixation. With the diagnosis of PLO, the patient was treated with weaning, bisphosphonate, and supplementation of calcium carbonate and vitamin D. During the 12-month follow-up period, the results of DEXA and laboratory examination improved gradually, and the internal fixation was removed 12 months after surgery.

CONCLUSION

Orthopedic doctors should not ignore the possibility of PLO to avoid misdiagnosis of perinatal women with fractures. Improvement of functional recovery of fractures can be achieved with accurate diagnosis and individual treatment.

Barton Fracture of the Distal Radius in Pregnancy and Lactation-Associated Osteoporosis: A Case Report and Literature Review

Objective

Pregnancy and lactation-associated osteoporosis (PLO) is very rare, which typically occurs during the third trimester or during lactation. Many cases of PLO are associated with vertebral compression fractures or hip fractures, while distal radius fractures in patients with PLO are rarely reported.

Case Report

A 36-year-old patient presented with Barton fracture at 37 weeks of gestation. Temporary closed reduction and plaster external fixation were performed in emergency room. At 38 weeks of gestation, she gave birth to a healthy boy and began breastfeeding after delivery. Three days after delivery, the patient was admitted to the orthopedic ward for surgery and was diagnosed as PLO. The patient underwent open reduction and internal fixation and treated with weaning and supplementation of calcium carbonate and vitamin D. During the 1-year follow-up period, the results of laboratory tests and bone mineral density gradually returned to normal.

Conclusion

Clinicians should be alert to the possibility of PLO to avoid missed diagnosis. Accurate diagnosis and individualized treatment are of great significance for relieving pain and functional recovery of patients.

Pregnancy and lactation, a challenge for the skeleton

In this review we discuss skeletal adaptations to the demanding situation of pregnancy and lactation. Calcium demands are increased during pregnancy and lactation, and this is effectuated by a complex series of hormonal changes. The changes in bone structure at the tissue and whole bone level observed during pregnancy and lactation appear to largely recover over time. The magnitude of the changes observed during lactation may relate to the volume and duration of breastfeeding and return to regular menses. Studies examining long-term consequences of pregnancy and lactation suggest that there are small, site-specific benefits to bone density and that bone geometry may also be affected. Pregnancy- and lactation-induced osteoporosis (PLO) is a rare disease for which the pathophysiological mechanism is as yet incompletely known; here, we discuss and speculate on the possible roles of genetics, oxytocin, sympathetic tone and bone marrow fat. Finally, we discuss fracture healing during pregnancy and lactation and the effects of estrogen on this process.

Women With Pregnancy and Lactation-Associated Osteoporosis (PLO) Have Low Bone Remodeling Rates at the Tissue Level

Pregnancy and lactation-associated osteoporosis (PLO) is a rare, severe, early form of osteoporosis in which young women present with fractures, usually multiple vertebral fractures, during late pregnancy or lactation. In studies of idiopathic osteoporosis (IOP) in premenopausal women, we enrolled 78 women with low-trauma fractures and 40 healthy controls, all with normal menses and no secondary cause of bone loss. In 15 of the affected women, the PLO subgroup, fractures had occurred during late pregnancy or lactation. We hypothesized that clinical, bone structural, and metabolic characteristics would differ between women with PLO and those with (non-PLO) IOP and controls. All were evaluated > 12 months postpartum, when structural and remodeling characteristics would be expected to reflect baseline premenopausal status rather than transient postpartum changes. As previously reported, affected subjects (PLO and IOP) had BMD and microarchitectural deficiencies compared to controls. Women with PLO did not differ from those with IOP in terms of age, BMI, body fat, menarcheal age, parity, or age at first pregnancy. However, women with PLO had a more severe clinical presentation than those with IOP: more fractures (5.5 ± 3.3 versus 2.6 ± 2.1; p = 0.005); more vertebral fractures (80% versus 17%; p < 0.001); and higher prevalence of multiple fractures. BMD deficits were more profound and cortical width tended to be lower in PLO. PLO subjects also had significantly lower tissue-level mineral apposition rate and bone formation rates (0.005 ± 0.005 versus 0.011 ± 0.010 mm² /mm/year; p = 0.006), as well as lower serum P1NP (33 ± 12 versus 44 ± 18 µg/L; p = 0.02) and CTX (257 ± 102 versus 355 ± 193 pg/mL; p = 0.01) than IOP. The finding that women with PLO have a low bone remodeling state assessed more than a year postpartum increases our understanding of the pathogenic mechanism of PLO. We conclude that women with PLO may have underlying osteoblast functional deficits which could affect their therapeutic response to osteoanabolic medications. © 2019 American Society for Bone and Mineral Research.

Pregnancy-related osteoporotic vertebral compression fractures in two patients treated with low-molecular-weight heparin during pregnancy: case reports

Pregnancy-related osteoporosis (PRO) is an uncommon metabolic bone disease that can result in vertebral fragility fractures. Here we report two cases of young women who had been previously treated with LMWH-enoxaparin and were diagnosed with PRO with vertebral fragility fractures after delivery. In first case report, a 33-year-old primigravid woman who was treated with 40 mg/day of enoxaparin for eight months to prevent venous thromboembolism was presented. After delivery, Dual energy X ray absorptiometry (DEXA) revealed osteoporosis in lumbar and femoral neck region. In magnetic resonance imaging (MRI), T4-T7 thoracic vertebral height losses were detected. In second case report, a 28-year-old primigravid woman which was treated with 40 mg/day enoxparin from the second month to the birth was presented. Osteoporosis in lumbar region was detected by DEXA. MRI revealed T12-L1 and L5 vertebral height losses. In conclusion, PRO can cause severe low back pain and should be considered in differential diagnosis. A detailed medical history should be essential to detect relationship between LMWH and PRO.

Changes in bone mineral density and bone turnover markers during treatment with teriparatide in pregnancy- and lactation-associated osteoporosis

CONTEXT

Teriparatide (TPTD) therapy has been proposed as a potential treatment strategy in severe cases of pregnancy- and lactation-associated osteoporosis (PLO) characterized by the occurrence of fragility fractures in the third trimester or early postpartum.

OBJECTIVE

To investigate the changes in bone mineral density (BMD) and bone turnover markers in patients with PLO with and without TPTD treatment.

DESIGN

Retrospective cohort study.

PATIENTS

Thirty-two patients with PLO who presented with multiple vertebral fractures to a tertiary institution between 2007 and 2015 were included.

MEASUREMENTS

Changes in BMD at the lumbar spine (LSBMD) and proximal femur after 12 months of daily subcutaneous injections of 20 μg TPTD (n = 27) were assessed. Subjects who rejected the TPTD treatment were used as controls (n = 5).

RESULTS

LSBMD increased in both subjects treated with TPTD and controls, with greater increases in the TPTD group (15.5 ± 6.6% vs 7.5 ± 7.1%, P = .020) after adjustment for age and baseline LSBMD. During follow-up, serum levels of osteocalcin (OCN) and C-telopeptide of type I collagen (CTX) increased significantly in the TPTD group. In multivariate linear regression models, TPTD treatment (adjusted β = 7.92, P = .032) and younger age (adjusted β = 1.06, P = .046), but not baseline LSBMD, body mass index, serum OCN level and CTX level, were independently associated with greater increases in LSBMD.

CONCLUSIONS

In patients with PLO, LSBMD at 12 months increased in both the TPTD-treated and control groups. TPTD treatment and younger age were associated with greater increases in LSMBD irrespective of baseline LSBMD.

Pregnancy-related fractures: a retrospective study of a French cohort of 52 patients and review of the literature

A retrospective, multicentre study involving 52 patients was carried out to define the causes and characteristics of pregnancy-related osteoporosis. The mean number of vertebral fractures occurring during the last trimester of pregnancy or at the time of delivery was 3.8. This is often promoted by risk factors before or during pregnancy.

INTRODUCTION

In order to define the causes or predisposing factors of pregnancy-related osteoporosis and its clinical, radiological and bone density characteristics, laboratory findings, course and outcome, we carried out a retrospective multicentre study.

METHODS

The records of 52 women hospitalised over the last 10 years in the rheumatology departments of six French university hospitals and with a diagnosis of pregnancy-related osteoporosis were examined.

RESULTS

The patients' mean age at time of fracture was 32.1 years. In 10 patients, the fractures had occurred during the last trimester of pregnancy, and in 36 at the time of delivery or during the first 2 months post-partum. The mean number of vertebral fractures was 3.8 ± 2.0. Thirty three of the 52 patients had a risk factor of low bone mass before pregnancy. Twelve had disorders or treatments (heparin) that might promote osteoporosis during pregnancy, while 14 had no trigger factors before or during pregnancy. Overall, phosphate and calcium levels were normal, except for hyperphosphoraemia in lactating women (90%). On DXA scan, osteoporosis predominated in the trabecular bone (spinal T-score - 3.4, hip T-score - 2). Only 10 patients had a repeat fracture, and the increase in bone mineral density during follow-up was considerable, and improved by bisphosphonates (annual gain + 10% in the spine) or teriparatide (+ 15%).

CONCLUSIONS

Pregnancy-related osteoporosis gives rise to multiple vertebral fractures. It is often promoted by risk factors before or during pregnancy. Its mechanism is still unknown. Treatment with bisphosphonates or teriparatide appears to improve the recovery of bone mineral density.

Approach to the patient with pregnancy and lactation-associated osteoporosis: A case report and a review of the literature

RATIONALE

Pregnancy and lactation-associated osteoporosis (PLO) is very rare, but it can cause severe vertebral compression fractures with disabling back pain. Although it is a rare, PLO must be kept in mind in the differential diagnosis in patients presenting with low back pain during or after pregnancy.

PATIENT CONCERNS

A 23-year-old woman who suffered from lumbago and fractures in the vertebral column 1 month after delivery.

DIAGNOSIS

Pregnancy and lactation-associated osteoporosis.

INTERVENTIONS

Combination therapy of calcium and vitamin D were used for treatment, as well as regular follow-up.

OUTCOMES

The patient's back pain had decreased significantly, the bone metabolic index, bone mineral density (BMD) had improved and she did not experience any recurrence.

LESSONS

Early diagnosis and treatment of calcium and vitamin D, as well as the efficacy of PLO intervention monitoring and evaluation are critical for the success of treatment.

Two cases of pregnancy- and lactation- associated osteoporosis successfully treated with denosumab

Case 1. A 35-year-old woman in the 8^th month of her first pregnancy suffered acute lumbar pain that persisted for 4 months. In the 5^th month postpartum an acute increase in the low back pain led to a MRI which showed recent deformity in L1 and deformities of undetermined time of evolution in L2, L4, and L5. Laboratory evaluation did not reveal metabolic derangements. She had low bone mineral density (BMD, DXA) and severe deterioration of the microarchitecture of distal appendicular bone (HR-pQCT). Kyphoplasty of all 4 vertebrae was performed in 2 stages, and treatment with subcutaneous denosumab, 60 mg every 6 months, was begun. There was rapid and almost complete improvement in pain. An increase in trabecular bone was documented with HR-pQCT. Case 2. A 33-year-old mother who was breastfeeding her first-born child experimented acute dorsal pain. RMI revealed partial compression fractures in vertebrae D5-7. Her axial BMD was low. There was no family history of osteoporosis, and causes of secondary osteoporosis were ruled out. Her pain slowly subsided with conservative measures, oral analgesics, and nasal calcitonin. Then, treatment with oral strontium ranelate was prescribed; after 3 months serum alkaline phosphatase and osteocalcin had not increased, and after one year lumbar bone mineral density (BMD) was unchanged. Treatment was switched to subcutaneous denosumab. After one year, lumbar BMD had increased 14%, and the pain had almost completely subsided.

Pregnancy-related osteoporosis and spinal fractures

Pregnancy-related osteoporosis is a very rare condition characterized by the occurrence of fracture during pregnancy or the puerperium. Despite its relative rarity, it can be a dangerous condition that causes severe back pain, height loss and disability. Normal physiologic changes during pregnancy, genetic or racial difference, obstetrical history and obstetrical disease, such as preterm labor or pregnancy-induced hypertension, are presumed risk factors of pregnancy-related osteooporosis. However, exact etiology and pathogenesis are uncertain. The management and natural history are still poorly defined. Traditional medications for osteoporosis are calcium/vitamin D and bisphosphonate. Concerns with bisphosphonate include accumulation in bone and fetal exposure in subsequent pregnancies. The newly developed medication, teriparatide, has shown good results. We report six cases of pregnancy-related osteoporosis and spinal fracture with literature review.

Successful neridronate therapy in pregnancy-associated osteoporosis

Pregnancy-associated osteoporosis is a rare condition. The pathogenesis is probably multifactorial but has not yet been completely clarified. In this case report, a 38-year-old woman was referred to hospital after suffering an acute, non-traumatic back pain one month after delivering her first child. The radiological examination revealed four vertebral fractures. Bone mineral density was reduced, particularly at spine level. Biochemical tests were within normal range, except for increased urinary deoxypyridinoline and a slight reduction of the serum 25-OH vitamin D level. The patient was treated with neridronate, calcium and cholecalciferol. After one month, the patient was free of pain and DXA measurement after six months showed a marked recovery of bone mineral density at the spine and hip level.

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.

Postpartum sacral insufficiency fractures

Postpartum sacral insufficiency fracture is an uncommon occurrence that is often under-diagnosed because its symptoms of low back, buttock and groin pains may initially be attributed to physiologic biomechanical changes caused by pregnancy or to intervertebral disc disease. We present a case of bilateral sacral insufficiency fractures in a 37-year-old postpartum woman with osteopenic bone mineral density confirmed by dual energy X-ray absorptiometry. The symptoms were initially suspected to be of discogenic cause, and the fractures were incidentally appreciated at the edge of a lumbar spine magnetic resonance image. Therefore, it is important to keep in mind this potential diagnosis when examining imaging studies of postpartum patients. For women who present other risk factors of osteoporosis, imaging of the entire sacrum should be part of the imaging studies. If sacral stress fractures are diagnosed, further evaluation for bone mineral density and underlying metabolic bone disease is recommended.

Spinal compression fractures due to pregnancy-associated osteoporosis

OBJECTIVES

To report on unique cases of spinal compression fractures due to pregnancy-associated osteoporosis (PAO) and to suggest a satisfactory treatment modality.

MATERIALS AND METHODS

A single-center retrospective study. We reviewed the data of 535 patients with osteoporotic spinal compression fractures over a period of 5-year. Two patients who developed spinal compression fractures due to PAO were identified and treated.

RESULTS

The clinical presentation and blood investigations ruled out other causes of osteoporosis. Dual-energy X-ray absorptiometry was used to confirm the diagnosis. All patients improved with medical management.

CONCLUSION

Vertebral fractures due to PAO should be considered as a differential diagnosis in patients with back pain who are in the third trimester of pregnancy or in postpartum. Early recognition and appropriate conservative management would be necessary to prevent complications such as new vertebral fractures and chronic back pain.

Rare causes of osteoporosis

Osteoporosis is a metabolic bone disease characterized by loss of bone mass and strength, resulting in increased risk of fractures. It is classically divided into primary (post-menopausal or senile), secondary and idiopathic forms. There are many rare diseases, that cause directly or indirectly osteoporosis. The identification and classification of most of these rare causes of osteoporosis is crucial for the specialists in endocrinology and not, in order to prevent this bone complication and to provide for an early therapy. Several pathogenic mechanisms are involved, including various aspects of bone metabolism such as: decreased bone formation, increased bone resorption, altered calcium, phosphorus and/or vitamin D homeostasis, and abnormal collagen synthesis. In this review, less common forms of primary and secondary osteoporosis are described, specifying, if applicable: genetic causes, epidemiology, clinical features, and pathogenic mechanisms causing osteoporosis. A greater awareness of all rare causes of osteoporosis could reduce the number of cases classified as idiopathic osteoporosis and allow the introduction of appropriate and timely treatments.

Pregnancy and Lactation-Associated Osteoporosis: Bone Histomorphometric Analysis and Response to Treatment with Zoledronic Acid

Pregnancy and lactation-associated osteoporosis (PAO) is a rare condition with little known pathophysiology. Most cases are diagnosed in the third trimester of pregnancy or in the first weeks postpartum, particularly in first pregnancies. Vertebral fractures are most commonly observed and characterised by prolonged severe pain, functional limitations and a loss of height. Measurements of bone mineral density and biochemical markers of bone remodelling are the clinical methods most commonly used for the management of these patients. However, a bone biopsy with histomorphometric analysis has been considered to be the gold-standard. Few studies have evaluated the histomorphometry in patients with this clinical condition and none of them performed the procedure at the beginning of the clinical assessment. In this study, we report a case of PAO in a 31-year-old postpartum patient who had undergone a twin pregnancy. We describe the clinical, laboratory tests and imaging features. Bone histomorphometry showed a high resorption rate and excellent evolution after 1 year of treatment with intravenous zoledronic acid. Our data suggest that osteoclastogenesis plays a central role in the pathophysiological processes of this disease.

A case series of pregnancy- and lactation-associated osteoporosis and a review of the literature

The syndrome of pregnancy- and lactation-associated osteoporosis is a rare disorder whose precise etiology and treatment are largely unknown. We herein report two such cases occurring in the early postpartum period that led to multiple fragility compression fractures. Combination therapy of vitamin D and vitamin K enabled a marked gradual increase in bone mineral density.

Presentation and management of osteoporosis presenting in association with pregnancy or lactation

In this review, we summarize our current understanding of the pathophysiology of fragility fractures that occur for the first time during pregnancy and lactation, and provide guidance on appropriate investigations and treatment strategies. Most affected women will have had no prior bone density reading, and so the extent of bone loss that may have occurred during pregnancy or lactation is uncertain. During pregnancy, intestinal calcium absorption doubles in order to meet the fetal demand for calcium, but if maternal intake of calcium is insufficient to meet the combined needs of the mother and baby, the maternal skeleton will undergo resorption during the third trimester. During lactation, several hormonal changes, independent of maternal calcium intake, program a 5-10 % loss of trabecular mineral content in order to provide calcium to milk. After weaning the baby, the maternal skeleton is normally restored to its prior mineral content and strength. This physiological bone resorption during reproduction does not normally cause fractures; instead, women who do fracture are more likely to have additional secondary causes of bone loss and fragility. Transient osteoporosis of the hip may affect one or both femoral heads during pregnancy but it involves localized edema and not skeletal resorption. Case reports have described the use of calcitonin, bisphosphonates, strontium ranelate, teriparatide, vertebroplasty, and kyphoplasty to treat post-partum vertebral fractures. However, the need for such treatments is uncertain given that a progressive increase in bone mass subsequently occurs in most women who present with a fracture during pregnancy or lactation.

Post Pregnancy Severe Spinal Osteoporosis with Multiple Vertebral Fractures and Kyphoscoliosis in a Multigravida: A Rare Case with Management

Osteoporosis associated with pregnancy and lactation is a less commonly known condition and often overlooked. The prevalence, exact aetiology and its pathogenesis are unknown. It is commonly seen in first three months after delivery in primigravida. It is often undiagnosed because of it not suspected n and X-rays and densitometry are avoided if possible during pregnancy and lactation. If missed, it can lead to osteoporotic fractures and disability. In this paper, we report a case of a 24-year-old multigravida 4 months after pregnancy with multiple vertebral compression fractures and kyphoscoliosis. Her metabolic workup was normal but bone densitometry revealed severe osteoporosis of the dorso-lumbar spine. Immediate weaning and antiresorptives like bisphosphonates and teriparatide are used as first line drugs to manage postpartum spinal osteoporosis. Our patient presented at 4 month lactation and did not want to wean her infant, so she was treated with total contact orthosis and took vitamin D and calcium. The pain was relieved within 3 months but there was no improvement in bone density. After eight months when the infant was weaned, she was treated with teriparatide. After one year of teriparatide therapy, there were no new fractures and densitometry scores improved.

Bone metabolic changes during pregnancy: a period of vulnerability to osteoporosis and fracture

Changes in bone density and bone markers suggest that pregnancy is associated with deterioration of bone mass in the mother. The metabolism of calcium resets to allow for the needs imposed by the building of the fetal skeleton. The fetus contributes to the process through the output of regulators from the placenta. Understanding of the whole process is limited, but some changes are unambiguous. There is an increase in the circulating levels of vitamin D, but its functional impact is unclear. Fetal parathyroid hormone (PTH) and PTH-related peptide (PTHrp) play an indirect role through support of a calcium gradient that creates hypercalcemia in the fetus. Placental GH, which increases up to the end of pregnancy, may exert some anabolic effects, either directly or through the regulation of the IGF1 production. Other key regulators of bone metabolism, such as estrogens or prolactin, are elevated during pregnancy, but their role is uncertain. An increase in the ratio of receptor activator of nuclear factor kappa B ligand (RANKL) to osteoprotegerin (OPG) acts as an additional pro-resorbing factor in bone. The increase in bone resorption may lead to osteoporosis and fragility fracture, which have been diagnosed, although rarely. However, the condition is transitory as long-term studies do not link the number of pregnancies with osteoporosis. Prevention is limited by the lack of identifiable risk factors. When fractures are diagnosed, rest, analgesics, or, when indicated, orthopedic intervention have demonstrated efficacy. Systemic treatment with anti-osteoporotic drugs is effective, but the potential harm to the fetus imposes caution in their use.

Postpartum osteoporosis and vertebral fractures in two patients treated with enoxaparin during pregnancy

Postpartum osteoporosis (PPO) is a rare disease associated with pregnancy and lactation period. Here, we report severe PPO and multiple vertebral compression fractures in two patients treated with enoxaparin--low-molecular-weight heparin (LMWH)--throughout their pregnancy. A 34-year-old woman who has delivered her second baby 3 months ago presented with severe low-back pain. She was treated with enoxaparin 40 mg/day for 8 months during her pregnancy. Dual-energy X-ray absorptiometry (DEXA) showed low T- and Z-scores in lumbar (L) vertebras. In magnetic resonance imaging (MRI), severe height losses in thoracic (T) 12, L1, and L2 vertebras were detected. She was diagnosed to have severe PPO and multiple vertebral compression fractures and was prescribed risedronate 35 mg/week, calcium, and vitamin D. The other patient was a 36-year-old woman diagnosed with PPO and vertebral fractures at the third week postpartum. She was also treated with enoxaparin 60 mg/day during her pregnancy. Severe osteoporosis in L vertebras and height losses indicative for compression fractures in T5-8, T11-12, and L2-5 vertebras were detected by DEXA and MRI, respectively. She was treated with calcitonin 200 U/day, calcium, and vitamin D. These findings suggest that vertebral compression fractures and PPO may be one of the causes of severe back pain in postpartum patients. Treatment with LMWH during pregnancy might be considered as a new risk factor for this rare condition.

Osteoporosis presenting in pregnancy, puerperium, and lactation

PURPOSE OF REVIEW

To describe our current state of knowledge about the pathophysiology, incidence, and treatment of osteoporosis that presents during pregnancy, puerperium, and lactation.

RECENT FINDINGS

When vertebral fractures occur in pregnant or lactating women, it is usually unknown whether the skeleton was normal before pregnancy. Maternal adaptations increase bone resorption modestly during pregnancy but markedly during lactation. The net bone loss may occasionally precipitate fractures, especially in women who have underlying low bone mass or skeletal fragility prior to pregnancy. Bone mass and strength are normally restored postweaning. Transient osteoporosis of the hip is a sporadic disorder localized to one or both femoral heads; it is not due to generalized skeletal resorption. Anecdotal reports have used bisphosphonates, strontium ranelate, teriparatide, or vertebroplasty/kyphoplasty to treat postpartum vertebral fractures, but it is unclear whether these therapies had any added benefit over the spontaneous skeletal recovery that normally occurs after weaning.

SUMMARY

These relatively rare fragility fractures result from multifactorial causes, including skeletal disorders that precede pregnancy, and structural and metabolic stresses that can compromise skeletal strength during pregnancy and lactation. Further study is needed to determine when pharmacological or surgical therapy is warranted instead of conservative or expectant management.

A rare cause of postpartum low back pain: pregnancy- and lactation-associated osteoporosis

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare form of osteoporosis. It results in severe low back pain in the last trimester of pregnancy and in the postpartum period, decreases in height, and fragility fractures, particularly in the vertebra. The current case report presents a 32-year-old patient who presented with back and low back pain that began in the last trimester of the pregnancy and worsened at two months postpartum and who was diagnosed with pregnancy- and lactation-associated osteoporosis after exclusion of other causes; the findings are discussed in view of the current literature. PLO is a rare clinical condition causing significant disability. PLO must be kept in mind in the differential diagnosis in patients presenting with low back pain during or after pregnancy. The patients must be evaluated for the risk factors of PLO, and an appropriate therapy must be initiated.

Pregnancy-associated osteoporosis with a heterozygous deactivating LDL receptor-related protein 5 (LRP5) mutation and a homozygous methylenetetrahydrofolate reductase (MTHFR) polymorphism

Pregnancy-associated osteoporosis (PAO) is a rare, idiopathic disorder that usually presents with vertebral compression fractures (VCFs) within 6 months of a first pregnancy and delivery. Spontaneous improvement is typical. There is no known genetic basis for PAO. A 26-year-old primagravida with a neonatal history of unilateral blindness attributable to hyperplastic primary vitreous sustained postpartum VCFs consistent with PAO. Her low bone mineral density (BMD) seemed to respond to vitamin D and calcium therapy, with no fractures after her next successful pregnancy. Investigation of subsequent fetal losses revealed homozygosity for the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism associated both with fetal loss and with osteoporosis (OP). Because her neonatal unilateral blindness and OP were suggestive of loss-of-function mutation(s) in the gene that encodes LDL receptor-related protein 5 (LRP5), LRP5 exon and splice site sequencing was also performed. This revealed a unique heterozygous 12-bp deletion in exon 21 (c.4454_4465del, p.1485_1488del SSSS) in the patient, her mother and sons, but not her father or brother. Her mother had a normal BMD, no history of fractures, PAO, ophthalmopathy, or fetal loss. Her two sons had no ophthalmopathy and no skeletal issues. Her osteoporotic father (with a family history of blindness) and brother had low BMDs first documented at ages ∼40 and 32 years, respectively. Serum biochemical and bone turnover studies were unremarkable in all subjects. We postulate that our patient's heterozygous LRP5 mutation together with her homozygous MTHFR polymorphism likely predisposed her to low peak BMD. However, OP did not cosegregate in her family with the LRP5 mutation, the homozygous MTHFR polymorphism, or even the combination of the two, implicating additional genetic or nongenetic factors in her PAO. Nevertheless, exploration for potential genetic contributions to PAO may explain part of the pathogenesis of this enigmatic disorder and identify some at-risk women.

Osteoporotic vertebral fractures during pregnancy: be aware of a potential underlying genetic cause

CONTEXT

Although the baby growing in its mother's womb needs calcium for skeletal development, osteoporosis and fractures very rarely occur during pregnancy.

CASE PRESENTATION

A 27-year-old woman in the seventh month of her first pregnancy contracted midthoracic back pain after lifting an object. The pain was attributed to her pregnancy, but it remained postpartum. Her past medical history was uneventful, except for severely reduced vision of her left eye since birth. Family history revealed that her maternal grandmother had postmenopausal osteoporosis and her half-brother had three fractures during childhood after minor trauma. Her height was 1.58 m; she had no blue sclerae or joint hyperlaxity. Laboratory examination including serum calcium, phosphate, alkaline phosphatase, creatinine, β-carboxyterminal cross-linking telopeptide of type I collagen, 25-hydroxyvitamin D, and TSH was normal. Multiple thoracic vertebral fractures were diagnosed on x-ray examination, and dual-energy x-ray absorptiometry scanning showed severe osteoporosis (Z-scores: L2-L4, -5.6 SD; femur neck, -3.9 SD). DNA analyses revealed two compound heterozygous missense mutations in LRP5. The patient's mother carried one of the LRP5 mutations and was diagnosed with osteoporosis. Her half-brother, treated with cabergoline for a microprolactinoma, also had osteoporosis of the lumbar spine on dual-energy x-ray absorptiometry and carried the same LRP5 mutation. The patient was treated with risedronate for 2.5 years. Bone mineral density and back pain improved. She stopped bisphosphonate use 6 months before planning a second pregnancy.

CONCLUSION

Our patient was diagnosed with osteoporosis pseudoglioma syndrome/familial exudative vitreoretinopathy. Potential underlying genetic causes should be considered in pregnancy-associated osteoporosis with implications for patients and relatives. More studies regarding osteoporosis treatment preceding conception are desirable.

Pregnancy-associated osteoporosis with eight fractures in the vertebral column treated with kyphoplasty and bracing: a case report

Pregnancy-associated osteoporosis is a rare condition, which imposes multiple symptoms in the musculoskeletal system. Common complaints announced by patients are severe pain in the lower back, hips and the joints of the lower extremities with a reduced and less mobility status in general. Most of the patients' problems occur in the last trimester of pregnancy or postpartum and are often not diagnosed as side effects of osteoporosis but as problems associated with pregnancy. Although vertebral fractures are rare complications of pregnancy-associated osteoporosis, they should be always considered in women presenting with an acute pain syndrome in peripregnancy period. This case presents a 40-year-old primagravid woman who developed pain in hips and severe pain in the lower back causing an immobilization diagnosed with a pregnancy-associated osteoporosis with eight compression fractures in the thoracic and lumbar spine. Because of sagittal imbalance of the spine, she was treated with kyphoplasty at the four lumbar fractures and with bracing for the upper, thoracic ones, additional to the conservative anti-osteoporotic therapy. The authors discuss pregnancy-associated osteoporosis and its clinical presentation, as well as the indications of kyphoplasty, spinal alignment and the risk of single conservative treatment.

A case of teriparatide on pregnancy-induced osteoporosis

Pregnancy-induced osteoporosis is a rare disorder characterized by fragility fracture and low bone mineral density (BMD) during or shortly after pregnancy, and its etiology is still unclear. We experienced a case of a 39-year-old woman who suffered from lumbago 3 months after delivery. Biochemical evidence of increased bone resorption is observed without secondary causes of osteoporosis. Radiologic examination showed multiple compression fractures on her lumbar vertebrae. We report a case of patient with pregnancy-induced osteoporosis improved her clinical symptom, BMD and bone turnover marker after teriparatide therapy.

Upregulation of calcitriol during pregnancy and skeletal recovery after lactation do not require parathyroid hormone

Pregnancy invokes a doubling of intestinal calcium absorption whereas lactation programs skeletal resorption to provide calcium to milk. Postweaning bone formation restores the skeleton's bone mineral content (BMC), but the factors that regulate this are not established. We used Pth-null mice to test whether parathyroid hormone (PTH) is required for postweaning skeletal recovery. On a normal 1% calcium diet, wild-type (WT) and Pth-null mice each gained BMC during pregnancy, declined 15% to 18% below baseline during lactation, and restored the skeleton above baseline BMC within 14 days postweaning. A 2% calcium diet reduced the lactational decline in BMC without altering the gains achieved during pregnancy and postweaning. The hypocalcemia and hyperphosphatemia of Pth-null mice normalized during lactation and serum calcium remained normal during postweaning. Osteocalcin and propeptide of type 1 collagen (P1NP) each rose significantly after lactation to similar values in WT and Pth-null. Serum calcitriol increased fivefold during pregnancy in both genotypes whereas vitamin D binding protein levels were unchanged. Absence of PTH blocked a normal rise in fibroblast growth factor-23 (FGF23) during pregnancy despite high calcitriol. A 30-fold higher expression of Cyp27b1 in maternal kidneys versus placenta suggests that the pregnancy-related increase in calcitriol comes from the kidneys. Conversely, substantial placental expression of Cyp24a1 may contribute significantly to the metabolism of calcitriol. In conclusion, PTH is not required to upregulate renal expression of Cyp27b1 during pregnancy or to stimulate recovery from loss of BMC caused by lactation. A calcium-rich diet in rodents suppresses skeletal losses during lactation, unlike clinical trials that showed no effect of supplemental calcium on lactational decline in BMC.

Static and dynamic biomechanical adaptations of the lower limbs and gait pattern changes during pregnancy

The purpose of this literature review is to evaluate the studies that have investigated static and dynamic biomechanical changes of the lower limbs and gait patterns during pregnancy. Original articles on this subject, published between 1934 and 2012, were considered. In general, pregnant women demonstrated greater hip flexion, more extended knees and less plantar flexion ankles. These changes could explain the gait patterns of pregnant women characterized by increased hip angles, decreased propulsion forces associated with increased durations of stance phase and changes in distributions of the plantar loads with increased loads in the forefoot and decreased ones in the rearfoot. This can lead to arthrokinematic deviations that, with time, contribute to the development of musculoskeletal discomfort. In summary, these findings showed the importance of further longitudinal studies to investigate the relationships between musculoskeletal discomfort in pregnant women in the lower limbs and gait changes observed throughout this period.

Parathyroid and calcium metabolism disorders during pregnancy

Parathyroid disorders are not common among pregnant women, but harbor a significant morbidity and mortality potential if they remain unrecognized and untreated. The symptoms caused by abnormally low or high blood free calcium level are mostly non-specific in the initial stages, thus when recognized might pose a real danger. Here we will survey the alterations in calcium metabolism induced by pregnancy, and describe the clinical manifestations, diagnosis and treatment of parathyroid and other calcium metabolism disorders during pregnancy. The current literature on the impact of calcium and vitamin D deficiency during pregnancy will also be reviewed.

Effect of teriparatide on pregnancy and lactation-associated osteoporosis with multiple vertebral fractures

Pregnancy and lactation-associated osteoporosis (PLO) is very rare, but it can cause severe vertebral compression fractures with disabling back pain. PLO patients have commonly been treated with antiresorptive agents against high bone turnover. There are, however, some concerns regarding the use of bisphosphonates: (1) PLO occurs during the first pregnancy with a high possibility of recurrence during the second pregnancy, (2) long-term outcomes of bisphosphonates in PLO are lacking, and (3) there is a possibility of bisphosphonates accumulated in the bones crossing the placenta. Therefore, alternative therapies must be considered. We analyzed the effect of teriparatide (TPTD), the human recombinant parathyroid hormone (1-34), for 18 months in three women with PLO. Multiple vertebral fractures with severe back pain appeared within 6 months after their first childbirth. Two of them had a family history of osteoporosis. Lactation was discontinued immediately after diagnosis of PLO. Calcium carbonate, cholecalciferol, and TPTD were prescribed. The back pain immediately resolved. Bone mineral density (BMD) increased by 14.5-25.0% (mean 19.5%) at the lumbar spine and by 9.5-16.7% (mean 13.1%) at the femoral neck, after 18 months of treatment. The final Z scores in these PLO patients were nearly normalized. Two women had a second baby without any complication. BMD significantly improved after 18 months of treatment with TPTD without further fractures. In conclusion, TPTD should be considered to avoid long-term morbidity in young patients with PLO and is highly encouraged for use in PLO patients with multiple vertebral fractures.

Amelioration of pregnancy-associated osteoporosis after treatment with vitamin K₂: a report of four patients

Abstract We demonstrate for the first time therapeutic effects of vitamin K₂ (menatetrenone) on pregnancy-associated osteoporosis with multiple vertebral fractures in four cases. Due to its safety, vitamin K₂ presents itself as a treatment option for women with pregnancy-associated osteoporosis. Desirably, future controlled studies should verify these findings.

Calcium and bone disorders in pregnancy

Significant transplacental calcium transfer occurs during pregnancy, especially during the last trimester, to meet the demands of the rapidly mineralizing fetal skeleton. Similarly, there is an obligate loss of calcium in the breast milk during lactation. Both these result in considerable stress on the bone mineral homeostasis in the mother. The maternal adaptive mechanisms to conserve calcium are different in pregnancy and lactation. During pregnancy, increased intestinal absorption of calcium from the gut mainly due to higher generation of calcitriol (1,25 dihydroxy vitamin D) helps in maintaining maternal calcium levels. On the other hand, during lactation, the main compensatory mechanism is skeletal resorption due to increased generation of parathormone related peptide (PTHrP) from the breast. Previous studies suggest that in spite of considerable changes in bone mineral metabolism during pregnancy, parity and lactation are not significantly associated with future risk for osteoporosis. However, in India, the situation may not be the same as a significant proportion of pregnancies occur in the early twenties when peak bone mass is not yet achieved. Further, malnutrition, anemia and vitamin D deficiency are commonly encountered in this age group. This may have an impact on future bone health of the mother. It may also probably provide an opportunity for health care providers for prevention. Other metabolic bone diseases like hypoparathyroidism, hyperparathyroidism and pseudohypoparathyroidism are rarely encountered in pregnancy. Their clinical implications and management are also discussed.

Disorders of calcium metabolism and parathyroid disease

Pregnancy and lactation are associated with profound changes in calcium physiology. This can make interpretation of biochemical tests difficult during these times. Diseases of bone and calcium metabolism are uncommon during pregnancy but can be severe when they occur. These conditions are complicated by the need for dual consideration for the maternal and foetal health. These conditions are also much less well studied than related conditions that occur outside of pregnancy resulting in a reduction in evidence for and confidence in recommendations relating to management. This chapter will review the changes in calcium physiology that occur with pregnancy and lactation, describe the disorders of calcium and parathyroid physiology that can occur and outline the most appropriate way to manage these conditions.

Calcium and bone metabolism disorders during pregnancy and lactation

Pregnancy and lactation cause a substantial increase in demand for calcium that is met by different maternal adaptations within each period. Intestinal calcium absorption more than doubles during pregnancy, whereas the maternal skeleton resorbs to provide most of the calcium content of breast milk during lactation. These maternal adaptations also affect the presentation, diagnosis, and management of disorders of calcium and bone metabolism. Although some women may experience fragility fractures as a consequence of pregnancy or lactation, for most women, parity and lactation do not affect the long-term risks of low bone density, osteoporosis, or fracture.

Premenopausal osteoporosis: how to treat?

There is no agreement in defining osteoporosis in premenopausal women and diagnosis must be done carefully and not based on densitometric parameters. One must take into account the presence of other risk factors and history of fragility fractures, diseases or drugs that cause bone loss. Over 50% of premenopausal women with osteoporosis will have a secondary cause, with the remainder diagnosed with idiopathic osteoporosis. Therapeutic considerations are limited by a few studies in this group of patients, especially in regard to the risk of fractures. On the other hand, the FRAX index cannot be applied to premenopausal women. This article will review the measures to apply depending on the type of premenopausal osteoporosis, based on current scientific evidence.

Skeletal recovery after weaning does not require PTHrP

Mice lose 20% to 25% of trabecular bone mineral content (BMC) during lactation and restore it after weaning through unknown mechanisms. We found that tibial Pthrp mRNA expression was upregulated fivefold by 7 days after weaning versus end of lactation in wild-type (WT) mice. To determine whether parathyroid hormone-related protein (PTHrP) stimulates bone formation after weaning, we studied a conditional knockout in which PTHrP is deleted from preosteoblasts and osteoblasts by collagen I promoter-driven Cre (Cre(ColI) ). These mice are osteopenic as adults but have normal serum calcium, calcitriol, and parathyroid hormone (PTH). Pairs of Pthrp(flox/flox) ;Cre(ColI) (null) and WT;Cre(ColI) (WT) females were mated and studied through pregnancy, lactation, and 3 weeks of postweaning recovery. By end of lactation, both genotypes lost lumbar spine BMC: WT declined by 20.6% ± 3.3%, and null decreased by 22.5% ± 3.5% (p < .0001 versus baseline; p = NS between genotypes). During postweaning recovery, both restored BMC to baseline: WT to -3.6% ± 3.7% and null to 0.3% ± 3.7% (p = NS versus baseline or between genotypes). Similar loss and full recovery of BMC were seen at the whole body and hind limb. Histomorphometry confirmed that nulls had lower bone mass at baseline and that this was equal to the value achieved after weaning. Osteocalcin, propeptide of type 1 collagen (P1NP), and deoxypyridinoline increased equally during recovery in WT and null mice; PTH decreased and calcitriol increased equally; serum calcium was unchanged. Urine calcium increased during recovery but remained no different between genotypes. Although osteoblast-derived PTHrP is required to maintain adult bone mass and Pthrp mRNA upregulates in bone after weaning, it is not required for recovery of bone mass after lactation. The factors that stimulate postweaning bone formation remain unknown.