Calcium Metabolic Disorders in Pregnancy: Primary Hyperparathyroidism, Pregnancy-Induced Osteoporosis, and Vitamin D Deficiency in Pregnancy

Physiologic changes during pregnancy include calcium, phosphate, and calciotropic hormone status. Calcium metabolic disorders are rare in pregnancy and management with close calcium and vitamin D control and supplementation. Primary hyperparathyroidism is mostly asymptomatic and does not affect conception or pregnancy. It requires control of plasma calcium levels. Surgical intervention may be indicated. Data on severe cases are missing. Osteoporosis in or before pregnancy is rare but usually diagnosed from fractures. Medical treatment other than supplementation is contraindicated. Vitamin D deficiency is common and may affect conception and increase complications. Current evidence does not prove vitamin D supplements effective in improving outcomes.

Hypercalciuria: diagnosis and management

Hypercalciuria may be due to increased bone resorption, increased intestinal absorption, increased renal excretion or due to hypophosphatemia. Examination of the serum for calcium, phosphorus, parathyroid hormone and 1,25(OH)2D3, and of the urine for calcium, phosphorus and cyclic AMP will help arrive at the correct diagnosis. Therapies specific for each type of hypercalciuria are available and can be used. However, a more simplified diagnostic approach, and the use of thiazide diuretics for therapy, will usually suffice in the majority of patients.

Childhood idiopathic hypercalciuria

OBJECTIVE

To evaluate the clinical significance of renal calyceal microlithiasis (RCM) in children with idiopathic hypercalciuria (IHC).

MATERIAL AND METHODS

RCM is a renal echographic finding defined as the presence of hyperechogenic spots < 3 mm in diameter in the renal calyces. These spots have been associated with the presence of nephrourological symptoms in children and are considered to represent a stage prior to urolithiasis. We reviewed the medical records of 103 children (63 girls, 40 boys; age range 1-14 years; mean age 6.57 years) referred for various complaints who had IHC. Renal echography was routinely performed. At diagnosis, 52 children had RCM, 35 showed normal echography, 14 had calculi and two presented nephrocalcinosis. A long-term follow-up study was carried out to compare the clinical manifestations, analytic data and renal echographic findings of patients with RCM and those with normal echography.

RESULTS

The clinical manifestations and the results of biochemical studies did not differ significantly between the two groups. Renal sonographic findings during the follow-up period revealed that, of patients with initial RCM, 35 showed normalized sonographic findings, two developed calculi and 36 developed recurrent RCM. Of the children with normal initial echography, 17 developed RCM and three developed calculi. The risk of developing lithiasis was less in children with RCM than in those with normal initial renal echography (0.04 vs 0.09), the relative risk being 0.45 (95% CI 0.08-2.55). The clinical and analytic differences between the group of 14 children with initial lithiasis and the other two groups previously described were also analyzed and no significant differences were found. An ongoing echographic study of these patients showed that the echograph was normalized in 10 children at some point or other, while seven developed RCM (four unilateral, three bilateral). In 13 cases the lithiasis reappeared, and the relative risk of recurrent lithiasis compared with those who initially showed no lithiasis was 16.16 (CI 95% 6.81-38.31).

CONCLUSION

Our results indicate that up to 85% of children with IHC presented RCM in follow-up sonographies. This echographic finding, which may appear and disappear at different points during follow-up, does not seem to indicate an increased risk of lithiasis.

Disorders of calcium metabolism

Hypocalcaemia not associated with hypoalbuminaemia or 25(OH)-Vitamin D deficiency is rare and should be referred to a specialist clinic. 25(OH)-Vitamin D deficiency can often be treated safely by GPs, unless it is associated with renal impairment and secondary hyperparathyroidism, in which case a nephrology referral is required. An endocrine referral is required if deficiency is associated with pregnancy, co-existent primary hyperparathyroidism or the patient is receiving warfarin. The key role of the GP in managing hypercalcaemia is to distinguish between malignant and parathyroid causes in order to make the appropriate specialist referral (oncology, endocrine or renal). Severe hypercalcaemia (greater than 3.5 mmol/L or hypercalcaemia with dehydration, abdominal pain or reduced consciousness is a medical emergency.

Medical evaluation and treatment of urolithiasis

Nephrolithiasis is responsible for 1 in 1000 to 1 in 7600 pediatric hospital admissions annually throughout the United States. Seventy-five percent of children with nephrolithiasis have an identifiable predisposition to stone formation. This article reviews the different causes and disease states associated with nephrolithiasis in the pediatric population. The initial evaluation and the metabolic evaluation of children with nephrolithiasis are reviewed. Treatment modalities for the different stone types are also described.

Fatty acids and idiopathic calcium nephrolithiasis

Clinical and experimental investigations seem to underline the important role of fatty acids in the pathogenesis of hypercalciuria, a well-known risk factor for lithogenesis. To evaluate the relationships between the previously reported increase in plasma phospholipid arachidonic acid level and the factors responsible for calcium metabolism in idiopathic calcium nephrolithiasis, a best-fit model was constructed. This new statistical application shows a causal relationship between plasma phospholipid arachidonic acid content, intestinal calcium absorption, biochemical markers of bone turnover, urinary calcium excretion and bone mineral density at the lumbar spine. This model suggests that a defect in the phospholipid fatty acid composition could represent the primary event responsible for the mosaic of metabolic and clinical alterations that are distinctive features of renal stone formers, such as kidney, intestine, and bone calcium metabolism, and several forms of idiopathic hypercalciuria.

Increased gastrin and calcitonin secretion after oral calcium or peptones administration in patients with hypercalciuria: a clue to an alteration in calcium-sensing receptor activity

The calcium-sensing receptor (CaSR) has been detected in human antral gastrin-secreting cells, where, upon calcium and/or amino acid allosteric activation, it stimulates gastrin secretion. Patients with absorptive hypercalciuria (AH) display an enhanced gastric acid output; therefore, we evaluated the secretion of gastrin in subjects with AH (30 subjects vs. 30 healthy female controls, all postmenopausal) after oral calcium administration (1 g calcium gluconate) and, on a separate occasion, after peptone loading test (protein hydrolyzed, 10 g). Gastrin and monomeric calcitonin responses were higher in AH after both oral calcium administration (P < 0.01) and peptone loading (P < 0.01). Because the activation of CaSR by oral calcium and peptones directly induces gastrin release, the higher gastrin responses to these stimuli suggest an increased sensitivity of gastrin-secreting cells CaSR in patients with AH. A similar alteration in thyroid C cells might explain the enhanced calcitonin responses to both calcium and peptones. If the same alterations should in addition be present in the distal tubule (where CaSR is expressed as well), then a possible explanation for amino acid-induced hypercalciuria in AH would have been identified.

Endocrine disorders in the neonate

There is a significant amount of knowledge that has been gained in recent years in the study of endocrine disorders in the newborn. The explosion of genetic data shedding light on the origins of endocrine disease has expanded the level of diagnostic evaluation and management of these infants. This article provides a general review of endocrine disorders as they present in a newborn.

Idiopathic hypercalciuria in children--how valid are the existing diagnostic criteria?

Idiopathic hypercalciuria is a common metabolic abnormality in children of all ages. There is evidence of an association of idiopathic hypercalciuria with nephrolithiasis, hematuria, and osteoporosis. However, much of this evidence is anecdotal and the precise role of hypercalciuria in the pathogenesis of these conditions is far from clear. Furthermore, the precise definition of idiopathic hypercalciuria has not yet been established. The methodologies for quantitating urinary calcium excretion have also not been standardized, adding another potential confounding factor to the accurate interpretation of urinary calcium excretion. Long-term studies on the natural history of unselected children with idiopathic hypercalciuria are needed to establish the true clinical significance of this condition. The focus of this review is to critically evaluate the methods currently being used to measure urinary calcium excretion in children and to assess the validity of existing criteria for diagnosing idiopathic hypercalciuria.

Bone mass loss in calcium stone disease: focus on hypercalciuria and metabolic factors

BACKGROUND

Several authors have observed that idiopathic calcium stone formers show a bone mass reduction, which is more evident in those with idiopathic hypercalciuria. The aim of this work was the evaluation of osteopenia and osteoporosis rate in a group of idiopathic calcium stone formers. The influence of hypercalciuria, nutritional factors and anthropometric parameters on bone mass was evaluated in these patients as well.

METHODS

We enrolled 196 idiopathic calcium stone formers; 102 males, and 94 females. All subjects underwent a metabolic study. BMC and BMD were evaluated as well as QUS.

RESULTS

Males showed greater weight, height, BMI, densitometric values and plasma creatinine, uric acid, urea, sodium, magnesium, GFR and urinary osmolarity than females. Moreover males excreted more uric acid, urea, creatinine, sulphate, phosphate, oxalate and citrate than females. The prevalence of osteopenia and osteoporosis, according to T-score, was 54% and 14% respectively. Hypercalciuria was demonstrated in 21.7% of the patients. Hypercalciuric men showed a higher excretion of urea, phosphate, sulphate and magnesium.

CONCLUSIONS

Our results confirm the importance of QUS in the evaluation of stone formers' bone mass. Anthropometric characteristics and dietary habits seem to play a role in bone loss. We did not demonstrate any influence of hypercalciuria on bone mass. Although the pathogenesis of bone loss in stone formers still remains unclear, it can be hypothesized that a slight degree of metabolic acidosis, probably of alimentary origin, may be involved in the reduction of bone mass.

Hypercalciuria in Beckwith-Wiedemann syndrome

We determined the incidence of hypercalciuria (HC) and its association with nephrocalcinosis and nephrolithiasis in 18 consecutive patients with Beckwith-Weidemann syndrome (BWS). Random, nonfasting urine samples were obtained from each patient. All patients had abdominal ultrasonography, most on several occasions. Four patients (22%) had HC. Of these, 2 had nephrocalcinosis, one had hyperechoic kidneys, and one had normal renal imaging. Serum calcium was normal in all patients with HC. Because we found that an increased prevalence in the occurrence of HC and its complications in a group of children with BWS, any child with BWS should be evaluated for HC.

Dynamic investigation for evaluation of calcium metabolism and parathyroid function

Differently from other metabolic conditions, most of calcium metabolism disorders are diagnosed through simple detection of both serum and urinary excretion (24-h urine collection), levels of calcium, total and ionized form, and phosphate, and of calciotropic hormone serum levels, such as calcitonin, PTH and vitamin D metabolites. For the diagnosis and clinical monitoring of some metabolic bone diseases, such as osteoporosis and Paget's disease, the assessment of bone turnover is offering a useful tool for the evaluation of the therapeutic response in affected individuals. Markers of bone formation are represented by bone alkaline phosphatase and osteocalcin, while principal bone resorption markers are represented by pyridinoline, deoxypyridinoline and crosslinks of collagen N-telopeptide, both in the 24-h and fasting second morning urine collection. Only in selected conditions, here briefly reviewed, dynamic tests can offer an interpretation on the pathogenetic events causing a disorder of calcium metabolism.

Update on the diagnosis and treatment of disorders of calcium regulation

The availability of PTH, iCa, PTHrP, and 25OHD assays for evaluation of calcium abnormalities in companion animals has been well received [table: see text] by clinicians and diagnosticians. Use of these assays has heightened awareness that some of these disorders are more common than originally thought. Also, there is added insight of alterations of calcium homeostasis as a consequence of other illness or environmental factors such as diet. Animal counterparts of other disorders of calcium metabolism in people are likely to be identified, and use of these assays should play a significant role. As already emphasized, the foundation of using [table: see text] these assays is first assessing whether the calcium abnormality is of a parathyroid-dependent or parathyroid-independent classification.

Feline endocrinology update

This article highlights the advances in feline endocrinology, excluding diabetes mellitus and hyperadrenocorticism, which have recently been reviewed elsewhere. The goal will be to provide clinically relevant information regarding pathogenesis, diagnosis, and treatment options for these feline endocrine disorders.

Metabolic disorder in myocardiac intracellular free calcium after thermal injury

Cutaneous burn trauma causes functional inhibition of the heart, but the mechanism is unclear. Using a high dissociation constant (K(D)) calcium indicator TF-BAPTA and 19F MR spectroscopy, the relationship between the changes of cytosolic free calcium and cardiac function after burn trauma was examined. Sprague-Dawley rats received scald (43% TBSA) or sham burns. Twenty-four hours later, the hearts were excised and perfused by the Langendorff method with a modified phosphate-free Krebs-Henseleit bicarbonate buffer. Left ventricular developed pressure (LVDP) was recorded through a catheter attached to an intraventricular balloon. At the same time, 31P and 19F nuclear magnetic resonance (NMR) spectroscopy was perforined before and after TF-BAPTA loading. LVDP of the heart from burned rats was 40% less than in sham burn rats (65+/-6 vs 110+/-12 mmHg, P<0.01). Cytosolic free calcium increased about four-fold in those hearts from the burn group compared to the sham burn group (0.807+/-0.192 vs 3.891+/-0.929 microM). Loading TF-BAPTA in those hearts only caused about a 15-20% decrease in LVDP. PCr/Pi ratio also decreased significantly with this loading, but ATP signals were not affected. In conclusion, the inhibition of cardiac contractility caused by burn trauma correlated with the overload of cytosolic free calcium in the heart.

Microgravity inhibits intestinal calcium absorption as shown by a stable strontium test

BACKGROUND

Little is known about the onset and degree of biochemical and functional alterations in calcium metabolism during microgravity.

OBJECTIVE

To evaluate the effect of microgravity on intestinal calcium absorption and calcium-regulating hormones under metabolic ward conditions.

MATERIALS AND METHODS

Fractional calcium absorption (Fc240 in percentage of dose administered) was determined pre-flight, in-flight and post-flight, by use of a stable strontium test in one cosmonaut who spent 20 days in space. Moreover, a sequence of blood samples was collected for the determination of serum parathyroid hormone (PTH), 25-hydroxyvitamin D, calcitriol and serum C-telopeptide (CTx, biomarker of bone resorption) levels. During all periods of data collection, calcium intake was held constant at a minimum level of 1.000 mg day(-1) and a daily supplement of 16.6 microg vitamin D2 was given. Personal ultraviolet (UV) light exposure was measured during the whole mission using a biologically weighting UV dosimeter.

RESULTS

Fc240 was markedly reduced on flight day 19 (4.4%) as compared to pre-flight and post-flight data (13.4% and 17.2%, respectively). Serum calcitriol levels fell from 40.6 pg mL(-1) (mean pre-flight level) to 1.3 pg mL(-1) on flight day 18 and returned into the normal range after recovery. Serum CTx increased during the flight, while serum PTH and 25-hydroxyvitamin D levels did not change significantly.

CONCLUSIONS

Intestinal calcium absorption can be diminished after only three weeks of microgravity. Changes are associated with a severe suppression of circulating calcitriol levels, but are independent of exogenous vitamin D supply and serum PTH levels.

Renal granulomatous sarcoidosis in childhood: a report of 11 cases and a review of the literature

We analysed retrospectively 11 children with renal granulomatous sarcoidosis confirmed by renal histology in order to describe the course and prognosis of the disease. Symptomatic sarcoidosis was diagnosed at a mean age of 10.1 years. Nine children had renal involvement at the time of diagnosis. In the course of the disease, nine patients developed renal failure and mild proteinuria, seven had transient sterile leukocyturia, four showed microscopic haematuria, seven had a urinary concentrating defect, and enlarged kidneys were seen in three patients. One child had hypercalcaemia and hypercalciuria, none had hypertension. Light microscopy of the kidney showed interstitial infiltration by mononuclear cells in all children, interstitial fibrosis in nine patients, epithelioid granulomas in seven, tubular involvement in eight, and mild glomerular involvement in seven patients. Renal immunofluorescence was negative. Ten children received prednisone for 1-11 years. After a mean follow up of 5.5 years, three patients had entered end-stage renal failure and one had chronic insufficiency after interruption of medical supervision and prednisone therapy.

CONCLUSION

Renal failure, proteinuria, leukocyturia, haematuria, and concentration defect are the prominent features of renal granulomatous sarcoidosis in children. Steroid therapy, adjusted according to disease activity, may prevent end-stage renal failure.

Think of genetic hypercalciuria when a child has urinary tract findings

Genetic hypercalciuria, one of the most common mineral disorders in childhood, is frequently associated with a variety of urinary tract problems. Identifying and treating genetic hypercalciuria alleviates urinary tract problems and optimizes peak bone mass growth in affected children. Advanced practice pediatric nurses play a key role in identifying and coordinating care for children with genetic hypercalciuria.

High prevalence of bone disorders after gastrectomy

BACKGROUND

Studies indicate that gastrectomy might alter calcium and bone metabolism, resulting in bone disorders. No data are currently available on the prevalence of bone disorders after gastrectomy.

METHODS

Sixty gastrectomy patients were investigated for serum parameters of calcium and bone metabolism 5 to 20 years postoperatively and compared to an age- and sex-matched healthy control population. Forty patients agreed to a radiological investigation of the spine by anterior-posterior and lateral radiographs of the thoracic and lumbar spine and by computed tomography (CT) osteodensitometry.

RESULTS

Serum calcium and 25-(OH)-vitamin D were decreased in gastrectomized patients, while parathyroid hormone and 1,25-(OH)2-vitamin D were increased. Serum parameters of calcium metabolism were altered in as many as 68% of patients. We found 31 vertebral fractures in 13 patients, 30 grade 2 vertebral deformities in 18 patients, and osteopenia in 15 patients, corresponding to a prevalence of 33%, 45%, and 37% in gastrectomized patients, respectively. The overall rate of gastrectomy patients having vertebral fractures and/or osteopenia was 55%. The risk of having a vertebral deformity was increased by more than sixfold after gastrectomy. Our study is the first report evaluating vertebral deformities in gastrectomized patients, and the largest series of gastrectomized patients investigated by CT osteodensitometry.

CONCLUSION

We found a high prevalence of bone disorders in gastrectomized patients, possibly resulting from disorders in calcium metabolism. Postgastrectomy bone disease might derive from a calcium deficit, which increases calcium release from bone and impairs calcification of newly build bone matrix.

[Studies of calcium metabolism in patients with hypercalciuria]

The different subgroups of hypercalciuria cannot be separated clearly by the Pak calcium-load test. To improve the diagnosis and therapy we examined all relevant parameters of calcium metabolism in 32 patients with calcium urolithiasis and hypercalciuria (> 6.25 mmol/day). We also conducted bone mineral density measurements as well as the Pak calcium-load test. In most cases the pathophysiological constellations which Pak takes as the basis for his classification of hypercalciuria could not be shown. To date, diagnostics only insufficiently explains the genesis of hypercalciuria (except pHPT). As a consequence, a therapeutic problem arises: a low-calcium diet should not be generally recommended, since some patients may develop osteopenia. From our investigation the following diagnostic and therapeutic conclusions can be drawn: (1) Hypercalciuria in primary hyperparathyroidism should be treated by surgical removal of the adenoma. (2) The parathormone-independent osteogenic form should be treated with thiazides. (3) Hypercalciuria with increased 1.25-dihydroxyvitamin D should be treated by low-calcium diet.

Investigation of calcium disorders

The advent of new two-site immunometric assays for intact parathyroid hormone (PTH) measurement has enhanced the interpretation of results in many patients under investigation for hypercalcemia. The aim of this article is to give practical advice on the use of the new intact PTH methods and other tests for the investigation of the more common disorders of calcium metabolism.

Calcium and phosphorus derangements

Derangements in plasma calcium and phosphorus concentrations can precipitate serious and life-threatening complications in critically ill patients. An understanding of the function and homeostasis of these ions is essential to fully comprehend the causes, clinical manifestations, and treatment of calcium and phosphorus imbalances. This article will help the critical care nurse to identify patients at risk, to recognize derangements early (while they are still mild), and to seek and monitor appropriate treatment.

[Hypercalciuria]

Hypercalciuria is the cause of almost 20% of all secondary osteoporoses and in 23% these cases are associated with calcium urolithiasis. It is therefore necessary to search for these patients actively because their treatment with hydrochlorothiazide and amiloride is easy and highly effective. We must not be satisfied with the finding of hypercalciuria as the only cause of demineralization of bone, as several causes may combine in a single patient. Comprehensive treatment of osteopenia associated with hypercalciuria is relatively shorter and more successful than in other forms of secondary osteopenias.

[The eye manifestations in phosphorus-calcium metabolic disorders]

The investigation of a number of 286 patients having disorders of binocular seeing shows a very frequent association of these to spasmophilia, especially for persons of feminine sex during their third or fourth decades of life. The medicamentous treatment of spasmophilia has ameliorated the disturbing binocular seeings, which had appeared again after stopping the treatment for a long time. The authors recommend the cover-test end the examination using Maddox's experiment for tracing rapidly out the binocular seeing disturbings. In order to stimulate the movements of the ocular globe in an reverse sense to the deviation formed by the oculomotor existed lack of poise, it had been used the prescription of classes with prisms assembled conversely to the classic rules, having the indication of wearing them for 3-4 hours a day.

[Bone density in idiopathic hypercalciuria in men. Study by dual photon absorptiometry, X-ray computed tomography and histomorphometry]

Lumbar bone mineral density (BMD) of the L3 vertebra was evaluated by double photon absorptiometry or tomodensitometry (TDM) in 55 hypercalciuric individuals in two separate studies. In the first, in a department of nephrology, 29 lithiasis patients were studied by TDM of L3. By this technique, trabecular density was 75 +/- 23% of normal. It was lower in the 17 patients in whom hypercalciuria persisted after calcium restriction (66 +/- 15% of normal and below the "fracture threshold" in 9 cases) than in the 12 patients in whom it disappeared after the prescription of such a diet (88 +/- 26%, below the "fracture threshold" in 3 cases), this difference being significant (p less than 0.01). In another 26 patients, seen in a department of rheumatology, three of whom had osteoporosis with vertebral fracture, density was measured in 21 cases by double photon absorptiometry (mean Z score -1.9 +/- 1.0) and in 5 cases by TDM (mean BMD of L3 69 +/- 21% of normal). Mean iliac trabecular volume, measured in 8 cases only, was 70 +/- 25% of normal and was below the "fracture threshold" in 3 cases. Comparison of the two study groups was not possible because of differences in recruitment and methods of investigation. These two studies nevertheless show the existence of significant vertebral bone rarefaction during hypercalciuria in the young man. Confirmed and quantified in patients in whom the metabolic disturbance was discovered as a result of radiological abnormalities, this quantitative abnormality was also seen in patients in whom hypercalciurie was found because of renal lithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for hypercalciuria

Reference values for the urinary calcium/creatinine ratio (Ca/Cr ratio) in the first morning urine were established in 361 healthy children aged 5 to 15 years, on unrestricted diets. The urinary Ca/Cr ratio in the urine upon arising was independent of sex but dependent upon age. The measurement of the urinary Ca/Cr ratio in the urine upon arising while on unrestricted diets may be a reasonable screening test for elevated calcium excretion. On the basis of the urinary Ca/Cr ratios in the urine upon arising during unrestricted diets and the calciuric response to calcium restricted diets and the oral calcium loading test, idiopathic hypercalciuria (IH) was subclassified into three groups: (1) absorptive hypercalciuria; (2) renal hypercalciuria; (3) dietary hypercalciuria. The pathogenesis of IH is controversial. Our data suggest that disordered 1,25 (OH)2 vitamin D metabolism with excessive urinary phosphate excretion occurs in absorptive hypercalciuria.

Atypical idiopathic hypercalciuria in an adolescent

Idiopathic hypercalciuria (IH) in adults is recognized as a cause of urolithiasis. If IH is symptomatic, the symptoms are hematuria, renal colic, or obstructive uropathy with or without infection. In children, IH has been linked to the spectrum of urinary symptoms including hematuria, pyuria, dysuria, recurrent urinary infections, abdominal or suprapubic pain, proteinuria, and the frequency-urgency syndrome. Hematuria may appear prior to the appearance of stones, and thiazide therapy appears to prevent stone formation by decreasing urinary calcium excretion. This report describes an older adolescent with hematuria and flank pain. His urinary chemistry values were not consistently typical of IH, but a thiazide trial with withdrawal challenge was diagnostic. His case is remarkable because, though essentially an adult, his disease was typical of prepubertal disease. Adolescents with unexplained urinary symptoms should be evaluated for IH. The urinary calcium-creatinine ratio may not be elevated, and timed urinary calcium may be equivocal. In some cases a thiazide trial may be valuable and cost effective.

Two-site assay of intact parathyroid hormone in the investigation of primary hyperparathyroidism and other disorders of calcium metabolism compared with a midregion assay

We compared the utility of measurements of serum intact human PTH-(1-84) and midregion human PTH-(44-68) in patients with disorders of extracellular calcium metabolism. Serum midregion PTH was determined by RIA, and serum intact PTH was measured by a sensitive and specific immunoradiometric two-site assay. The serum intact PTH concentrations in 70 patients with primary hyperparathyroidism were above the normal range in 69, and thus widely separated from the levels in 40 patients with hypercalcemia of malignancy, in whom serum intact PTH values were usually below normal. In contrast, both groups had overlapping serum midregion PTH values. In patients after renal transplantation and those with chronic renal failure, serum intact PTH levels were in the normal range twice as often as were serum midregion PTH values. The intact PTH assay was also superior in detecting venous gradients of the hormone and changes in PTH secretion caused by altered serum calcium concentrations, and serum intact PTH was remarkably low in hepatic venous effluent. We conclude that this new assay for serum intact PTH is superior to the midregion RIA in investigating parathyroid function in several different clinical conditions.

The use of an intact molecule parathyroid hormone assay in disorders of calcium metabolism

We present the results obtained using a 1-84 human parathyroid hormone (PTH) assay in patients with abnormal calcium metabolism. A normal range was established in a series of healthy volunteers. Patients with surgically proven hyperparathyroidism (HPT) showed increased PTH levels which were separate from the normal range. Patients with probable hyperparathyroidism and milder hypercalcaemia showed a raised median PTH level but the range overlapped with normal. Patients with hypercalcaemia of malignancy showed reduced PTH levels and these patients were readily differentiated from those with probable and proven HPT by the use of the assay. In patients with chronic renal failure PTH values ranged from normal to high, the PTH concentration was found to be correlated with plasma alkaline phosphatase, but not with plasma creatinine.

[Intact serum parathormone (PTH 1-84). A suitable parameter for the diagnosis of calcium metabolism disorders]

Intact parathormone (PTH 1-84) was measured with a new immunoradiometric method in serum from 83 children and adults with various abnormalities of calcium metabolism. The results were compared with those of an assay of midregional PTH fraction (44-68). Both measurements discriminated well between normal controls and patients with primary or secondary hyperparathyroidism. In patients in chronic renal failure intact PTH measurement was best for demonstrating parathyroid secretion. An important advantage of the new method is in the diagnosis of PTH hyposecretion in hypoparathyroidism and of tumour hypercalcaemia, which is not possible by mid-regional PTH determination. Intravenous injection of calcium (2 mg/kg over 5 min) and of synthetic PTH fragment (6 U/kg 1-38 hPTH over 2 min) caused a reduction in intact serum-PTH to about half the initial value after five minutes. Measuring intact PTH is thus a suitable method for determining both raised and decreased parathyroid secretion in disease and in the course of function tests. It is simple to perform, subject to only minor interference, and thus suitable also as a routine laboratory test.

Comparison of the hardness change and mineral loss in enamel by dimethyl ammonium fluoride (alpha C12 DMEAHF) or NaF treatment under intra oral cariogenicity test conditions

Changes in hardness as well as in Ca and P were determined in enamel slabs after treatment with 3% sucrose together with NaF or alpha C12 DMEAHF (both containing 0.006% F-) under Intra Oral Cariogenicity Test conditions. NaF treatment resulted in a hypermineralization of the surface of the enamel lesion suggesting formation of CaF2. Treatment with ammonium fluoride along with the same low F- concentration inhibits the caries process completely and seems to be a very promising anticaries agent.

Loading tests for diagnosis of metabolic anomalies in urinary stone formers

Four per cent of the population in the industrialized countries of Europe suffer once or several times from urinary calculus in the course of their lives. The high number of recurrences (50 to 60%) necessitates specific prophylaxis. Depending on the precise stone composition, a specific metabolic investigation should be undertaken in cases with recurrent urinary calculus. Within a special laboratory diagnostic program, all major anomalies can be diagnosed by means of loading tests. With the ammonium chloride loading test, renal tubular acidosis is diagnosed; the calcium loading test differentiates the types of hypercalciuria and the purine loading test verifies "latent hyperuricaemia".