Mild Idiopathic Infantile Hypercalcemia-Part 2: A Longitudinal Observational Study

CONTEXT

Idiopathic infantile hypercalcemia (IIH) is an uncommon disorder with variable clinical features. The natural history and response to dietary calcium and vitamin D restriction in IIH remains unclear.

OBJECTIVE

The aim of this study is to describe the clinical and biochemical response to dietary calcium and vitamin D restriction in a genetically characterized cohort of mild IIH.

METHODS

This is a longitudinal, observational cohort study of 20 children with mild IIH monitored for a median of 21months. Biochemical measures, dietary assessment, and yearly renal ultrasound results, since the time of diagnosis, were obtained and assessed prospectively every 4 to 6 months.

RESULTS

Median age at initial diagnosis was 4.5 months. Median levels of serum calcium (2.82 mmol/L) and 1,25 (OH)2D (192 pmol/L) were elevated, whereas serum PTH was reduced (10 ng/L). Urinary calcium:creatinine ratio was elevated for some, but not all individuals (median 1.49 mmol/mmol). All patients who were managed with a low-calcium diet showed an improvement in serum and urinary calcium measures, but the serum concentration of 1,25 dihydroxyvitamin D (1,25(OH)2D) and 1,25(OH)2D/PTH ratio remained elevated. In 2 of the 11 subjects, renal calcification worsened. There were no differences in response between individuals with CYP24A1 or SLC34A1/A3 variants.

CONCLUSION

The clinical presentation of mild IIH is variable, and dietary calcium and vitamin D restriction does not consistently normalize elevated 1,25(OH)2D concentrations or prevent worsening of renal calcification in all cases. Therapeutic options should target the defect in vitamin D metabolism.

The dietary management of calcium and phosphate in children with CKD stages 2-5 and on dialysis-clinical practice recommendation from the Pediatric Renal Nutrition Taskforce

In children with chronic kidney disease (CKD), optimal control of bone and mineral homeostasis is essential, not only for the prevention of debilitating skeletal complications and achieving adequate growth but also for preventing vascular calcification and cardiovascular disease. Complications of mineral bone disease (MBD) are common and contribute to the high morbidity and mortality seen in children with CKD. Although several studies describe the prevalence of abnormal calcium, phosphate, parathyroid hormone, and vitamin D levels as well as associated clinical and radiological complications and their medical management, little is known about the dietary requirements and management of calcium (Ca) and phosphate (P) in children with CKD. The Pediatric Renal Nutrition Taskforce (PRNT) is an international team of pediatric renal dietitians and pediatric nephrologists, who develop clinical practice recommendations (CPRs) for the nutritional management of various aspects of renal disease management in children. We present CPRs for the dietary intake of Ca and P in children with CKD stages 2-5 and on dialysis (CKD2-5D), describing the common Ca- and P-containing foods, the assessment of dietary Ca and P intake, requirements for Ca and P in healthy children and necessary modifications for children with CKD2-5D, and dietary management of hypo- and hypercalcemia and hyperphosphatemia. The statements have been graded, and statements with a low grade or those that are opinion-based must be carefully considered and adapted to individual patient needs based on the clinical judgment of the treating physician and dietitian. These CPRs will be regularly audited and updated by the PRNT.

Prevalence of coeliac disease in idiopathic hypoparathyroidism and effect of gluten-free diet on calcaemic control

BACKGROUND

Patients with idiopathic hypoparathyroidism (IH) require variable doses of calcium and 1-α-(OH)D. The reasons for such variability are not clear. As autoimmune mechanisms may play a role in IH, there is a possibility of coexistent coeliac disease with calcium/vitamin D malabsorption.

OBJECTIVE

We assessed the prevalence of coeliac disease and antitissue transglutaminase autoantibodies (anti-tTGAbs) in IH and analysed the effect of a gluten-free diet on calcaemic control.

METHOD

A total of 171 patients with IH and 126 healthy controls were screened for anti-tTGAb. IH patients with anti-tTGAb >20 RU/ml underwent duodenoscopy and intestinal biopsy; those with biopsy-proven coeliac disease were followed up on a gluten-free diet.

RESULTS

Eleven of 171 (6·4%) patients with IH and seven of 126 (5·6%) controls had anti-tTGAb (P = 0·81). There was no difference in the clinical and biochemical parameters at diagnosis and during long-term follow-up of 7·2 ± 4·8 year (mean serum total calcium = 1·88 ± 0·16 vs 1·82 ± 0·36 mmol/l, P = 0·52; phosphorus = 1·81 ± 0·17 vs 1·87 ± 0·36 mmol/l, P = 0·53) in IH patients with and without anti-tTGAb. Although CaSRAb positivity was comparable in the two groups, IH patients with anti-tTGAb had higher TPOAb positivity (45·5% vs 12·8%, P = 0·02). Coeliac disease was diagnosed in only 2/9 patients with IH on biopsy, both of whom showed improved calcaemic control with a gluten-free diet.

CONCLUSION

The prevalence of coeliac autoimmunity (6·4%) and coeliac disease (1·2%) in patients with IH seems to be similar to that in the general population. Notwithstanding this modest prevalence, it is important to be aware of the potential occurrence of coeliac disease with IH and the beneficial effect of a gluten-free diet on calcium control.

Importance of dietary calcium and vitamin D in the treatment of hypercalcaemia in Williams-Beuren syndrome

BACKGROUND

Williams-Beuren syndrome (WBS) is a rare genetic disorder caused by the deletion of 26-28 genes on chromosome 7. Fifteen percent of WBS patients present with hypercalcaemia during infancy, which is generally mild and resolves spontaneously before the age of 4 years. The mechanisms underlying the transient hypercalcaemia in WBS are poorly understood.

CASE

We report a case of severe symptomatic hypercalcaemia in a patient with WBS, in which treatment with mild calcium restriction, hyperhydration and repeated bisphosphonate administration only resulted in short-lasting effects. Long-term lowering of serum calcium was only achieved after reducing calcium and vitamin D intake to the bare minimum.

CONCLUSIONS

This case illustrates the potential severity of hypercalcaemia in WBS, and demonstrates that both the cause as well as the solution of this problem may be found in the intestinal absorption of calcium. We hypothesise that the phenotypical resemblance between WBS and transient idiopathic infantile hypercalcaemia can be explained by similarities in the underlying genetic defect. Patients suffering from transient infantile hypercalcaemia were recently described to have mutations in CYP24A1, the key enzyme in 1,25-dihydroxyvitamin D3 degradation. In the light of this new development we discuss the role of one of the deleted genes in WBS, Williams syndrome transcription factor (WSTF), in the etiology of hypercalcaemia in WBS.

Identification of AP2S1 mutation and effects of low calcium formula in an infant with hypercalcemia and hypercalciuria

CONTEXT

Although AP2S1 has recently been shown to be a causative gene for familial hypocalciuric hypercalcemia type 3 (FHH3), knowledge about FHH3 remains poor.

OBJECTIVE

Our objective was to report AP2S1 mutation and effects of low calcium formula in a patient with hypercalcemia and hypercalciuria.

PATIENT

This Japanese female infant was found to have hypercalcemia by a routine laboratory test for poor weight gain on breast feeding. At 49 days of age, serum calcium (adjusted by Payne's formula) was 13.1 mg/dL, intact PTH 27 pg/mL, and urinary calcium-to-creatinine ratio 1.29 mg/mg. There was no evidence for hyperparathyroidism, PTHrP-producing neoplasm, and vitamin D excess. These data, except for hypercalciuria, appeared to be consistent with defective calcium-sensing receptor-mediated signaling. With use of low calcium formula containing 2.6 mg/dL of calcium, she showed catch-up growth, and serum calcium was decreased, as was urinary calcium-to-creatinine ratio. Furthermore, feeding with a mixture of low calcium formula and standard formula with a 2:1 ratio maintained serum calcium ∼12 mg/dL without markedly increasing serum PTH.

RESULTS

Although no pathologic mutation was detected in CASR or GNA11, a presumably de novo heterozygous mutation (p.Arg15Leu), a previously reported causative mutation for FHH3, was identified in AP2S1 of this patient.

CONCLUSIONS

The results imply that lack of hypocalciuria does not necessarily argue against the presence of AP2S1 mutations. The early infantile age of this patient would have played a certain role in the occurrence of hypercalciuria, and low calcium formula is worth attempting in infants with FHH.

Subcutaneous fat necrosis of the newborn following hypothermia and complicated by pain and hypercalcaemia

A female infant was delivered at term with complications of severe meconium aspiration and birth asphyxia. Surface cooling was performed in the first 24 hours as part of the management of her birth asphyxia. Woody erythema was noted at 24 hours, followed by the formation of red-purple nodules on the 6th day. Clinical findings in the first 24 hours were suggestive of cold panniculitis. However, clinical and histological findings progressed to be in keeping with the diagnosis of subcutaneous fat necrosis of the newborn (SCFN). Furthermore, the immediate postnatal period was complicated by pain resistant to treatment with opiates. Asymptomatic hypercalcaemia was noted on periodic testing at 7 weeks and treated by rehydration, diuretics, prednisolone, etidronate and a low-calcium and -vitamin D diet. A review of the clinical and histological findings of the relevant panniculitides occurring in the postnatal period is presented, as well as a review of the treatment of hypercalcaemia in SCFN.

Vitamin D therapy in patients with chronic renal disease: the role of the renal dietitian

Chronic renal failure causes decreased vitamin D production, which profoundly alters parathyroid hormone (PTH) metabolism, and calcium and phosphorus balance. Correcting this deficiency is an important strategy in managing secondary hyperparathyroidism (SHPT) and helping to restore mineral balance. However, hypercalcemia and hyperphosphatemia are common side effects that hamper vitamin D hormone therapy by increasing dietary calcium and phosphorus absorption. This limitation has led to the development of D-hormone analogs that retain the ability to suppress PTH levels without causing drastic changes in calcium and phosphorus metabolism. These analogs have the potential to advance the management of SHPT. Renal dietitians can play a leading role in ensuring successful management of SHPT by participating in early patient intervention for abnormal mineral and vitamin D metabolism, by encouraging long-term phosphorus control, and by updating and implementing clinical protocols that promote optimal hormone levels (D and PTH), mineral levels (phosphorus and calcium), and nutritional factors.

Self-limited neonatal familial hyperparathyroidism associated with hypercalciuria and renal tubular acidosis in three siblings

Three siblings with neonatal familial hyperparathyroidism diagnosed at age 4 months, 2 months, and 5 days, respectively, were treated. Hypercalciuria, nephrocalcinosis, and renal tubular acidosis were present in each child. In all three, there were higher responses of serum parathyroid hormone to serum calcium and higher elevation of serum calcium with oral calcium loading. The metabolism of vitamin D and calcitonin seemed to be intact. Hypercalcemia associated with the abnormal response of parathyroid hormone secretion disappeared when the children passed the age of approximately 2 years, although renal tubular acidosis and nephrocalcinosis remained. An autosomal recessive inheritance seems likely.

Hypercalcaemia in a child with miliary tuberculosis

Hypercalcaemia and hypercalciuria were diagnosed in a 21-week-old boy with miliary tuberculosis. The tuberculosis was treated with isoniazid, rifampin and streptomycin. After 2 months, streptomycin was replaced by ethambutol. The hypercalcaemia was treated initially with prednisone, which decreased the serum 1.25 (OH)2 cholecalciferol level but the serum calcium level remained unaltered. After calcium and vitamin D restriction, the serum calcium level normalized within 1 day. The patient's tuberculosis was treated and he remains well.

Prevention of hypercalcemia-induced renal concentrating defect and tissue calcium accumulation

The mechanism of the concentrating defect of hypercalcemia is explored by examining the effect of concomitant phosphate restriction. Rats were pair fed a normal phosphorus diet, without (group 1) or with dihydrotachysterol (group 2), or a low-phosphorus diet (group 3). Hypercalcemia was comparable in groups 2 (12.1 +/- 0.6 mg/dl) and 3 (11.8 +/- 0.4 mg/dl), but serum phosphate was lower in group 3 than group 2 (3.8 +/- 0.7 vs. 7.1 +/- 1.1 mg/dl, P less than 0.005). Group 2 rats had impaired maximum urinary concentration after 24 h of fluid deprivation (2,441 +/- 450 mosmol/kg H2O, P less than 0.001) compared with group 1 (3,263 +/- 466 mosmol/kg H2O) or group 3 (3,332 +/- 515 mosmol/kg H2O) animals. Polydipsia and polyuria were found in group 2 rats only. Tubular calcium reabsorption was higher in group 2 (83.1 +/- 33.5 mg/24 h, P less than 0.001) than group 1 (47.0 +/- 26.1 mg/24 h) or group 3 (52.8 +/- 19.3 mg/24 h) animals, and medullary calcium concentration was higher in group 2 (7.57 +/- 3.08 nmol/mg dry wt, P less than 0.05) as compared to group 1 (5.04 +/- 1.37 nmol/mg dry wt) or group 3 (5.32 +/- 0.98 nmol/mg dry wt) rats. Total medullary solute concentration was significantly higher in group 3 than group 2 animals. Thus phosphate restriction prevents the defect of urinary concentrating ability of chronic hypercalcemia, probably by decreasing tubular uptake and tissue accumulation of calcium.

Elevated plasma 1,25-dihydroxyvitamin D concentrations in infants with hypercalcemia and an elfin facies

We measured plasma concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in the course of a 6-to-37-month survey of four children with hypercalcemia and an elfin facies (Williams syndrome). Levels of 1,25-(OH)2D were elevated (160 to 470 pg per milliliter) during the hypercalcemic phase of the disease, when the children were five to nine months old, and they decreased thereafter. Plasma 1,25 (OH)2D levels were higher than those found in three children (16 to 60 months old) with the elfin facies syndrome and no hypercalcemia (42 to 71 pg per milliliter) and eight children (1 to 36 months old) with hypercalcemia and no dysmorphy (12 to 140 pg per milliliter), including two children with vitamin D intoxication. Hypercalcemia in the three children with elfin facies was controlled by a low-calcium diet. Serum calcium levels fell to the normal range, and plasma 1,25-(OH)2D levels were normal for age (18 to 105 pg per milliliter) at 14 to 47 months of age, even after appropriate therapy had been discontinued. These observations suggest that hypercalcemia may be the consequence of abnormal synthesis or degradation of 1,25-(OH)2D in children with the elfin facies syndrome.

Milk alkali syndrome. Does it exist and can it be differentiated from primary hyperparathyroidism?

Four patients with milk-alkali syndrome (MAS) presented with many of the characteristics of primary hyperparathyroidism including hypercalcemia, low or normal serum phosphorus levels, normal or increased urinary calcium levels, and inappropriately high or elevated serum parathyroid hormone levels. These laboratory findings differ from those classically described in MAS, i.e., hypercalcemia without hypercalciuria and a normal or high plasma phosphate level. Because the serum calcium level failed to return to normal after two weeks of hydration and a low calcium diet, and because of the inability to distinguish this syndrome from primary hyperparathyroidism, two of the four patients underwent neck exploration. Four normal parathyroid glands were histologically proven in each, and at autopsy in a third patient, there was no evidence of parathyroid hyperplasia or adenoma. Hypercalcemia eventually resolved in all patients with a low-calcium diet for as long as six months. Of the several features of MAS, hypercalcemia, alkalosis in the presence of azotemia, a history of increased calcium and alkali intake, and a response to dietary calcium restriction are helpful in differentiating this syndrome from primary hyperparathyroidism. Laboratory tests in patients with MAS may be confusing and the return to normocalcemia in response to a calcium deficient diet may be delayed.

Subcutaneous fat necrosis of the newborn and idiopathic hypercalcemia. Report of a case

A female infant who was anoxic at birth had lesions of subcutaneous fat necrosis at the age of 16 days. She also had problems with poor feeding, frequent vomiting, and failure to thrive. Hypercalcemia was discovered at the age of 28 days and she died at 11 1/2 weeks despite return of the serum calcium level to normal with oral prednisone therapy and a diet low in calcium and devoid of vitamin D. Fourteen other cases of idiopathic hypercalcemia in patients with subcutaneous fat necrosis of the newborn have been reported. Most of these infants were full-term with prenatal complications. The hypercalcemia was usually diagnosed much later than the subcutaneous fat necrosis. Both conditions generally resolved without sequelae, but two of the 14 infants died. The causal relation between these two entities, if one exists, remains unknown. Infants with subcutaneous fat necrosis should have serial serum calcium determinations and should be observed closely for signs and symptoms of hypercalcemia, which include irritability, anorexia, constipation, and failure to thrive.

Immobilization hypercalcemia in spinal cord injury

Four patients having high-level quadriplegia developed elevated serum calcium concentrations (11 to 15.8 mg/100 ml) within three months of injury. All were young males (ages 15 to 19 years) and quadriplegic (C4-C7). Presenting symptoms were nausea, vomiting, polydipsia, polyuria and lethargy. In two patients severe muscle wasting and cachexia with clinical symptoms developed and persisted for several months. Laboratory studies in all patients showed negative calcium balance with hypercalciuria. Reduced renal function was seen in all patients but returned to normal with return of normal serum calcium. Alkaline phosphatase level was normal in three and elevated in one. Serum parathormone levels were normal. Roentgenograms revealed diffuse demineralization. Nephrocalcinosis and soft tissue calcifications developed in one patient. Primary treatment included reduced calcium intake, correction of dehydration, sodium infusion and remobilization. Corticosteroids, oral phosphates, furosemide and mithramycin were used with varying success to control prologned symptoms and severe hypercalcemia.

[Milk-alkali syndrome complicated by acute renal insufficiency]

A case of the "Burnett" syndrome complicated by acute renal insufficiency is reported. Hemodialysis and normalization of the diet helped in the end to eliminate both the milk-alkali syndrome and renal insufficiency.