Physician-induced hypocalcaemia, nephrocalcinosis, and incomplete distal renal tubular acidosis

Metabolic acidosis in renal transplantation: neglected but of potential clinical relevance

Chronic metabolic acidosis (CMA) is a common complication of the more advanced stages of chronic kidney diseases (CKD), and is associated with morbidity and mortality of CKD patients and possibly with the progression of renal disease. Nevertheless, there is limited evidence or information on the prevalence, the potential causal factors, the clinical impact and the effects of correction of CMA in kidney transplant recipients. In this review, we briefly look at the more relevant, though scanty, studies which have, over time, addressed the above-mentioned points, with the hope that in the future the interest of transplant nephrologists and surgeons will grow towards this unreasonably neglected issue.

Recombinant human parathyroid hormone therapy (1-34) in an adult patient with a gain-of-function mutation in the calcium-sensing receptor-a case report

OBJECTIVE

To describe a case of hypocalcemia in a patient with a gain-of-function mutation in the calcium-sensing receptor that was undetected until adulthood and successfully treated with recombinant parathyroid hormone.

METHODS

The clinical findings, laboratory data, and a review of the pertinent literature are presented.

RESULTS

A 55-year-old woman was hospitalized and seen by the endocrinology consult service for hypocalcemia that was refractory to repeated doses of intravenous calcium gluconate. She expressed concern about chronic leg muscle cramps and paresthesias of the lips and fingertips. In addition, she had no history of neck surgery, neck irradiation, or any autoimmune disease. She was a well-appearing female with no dysmorphic features or skin changes. Laboratory tests revealed hypocalcemia, hyperphosphatemia, hypomagnesemia, and hypovitaminosis D. Her parathyroid hormone concentration (PTH) was low at 14.2 pg/mL. Her PTH and calcium concentrations remained low despite repletion of magnesium and treatment with calcitriol and oral calcium replacement. A 24-hour collection for urinary calcium showed inappropriate hypercalciuria. Medical records showed her hypocalcemia to be chronic. Additionally, several family members had also complained of muscle cramps. A congenital cause of her hypoparathyroidism was considered, and genetic testing confirmed heterozygosity for a gain-of-function mutation in the calcium-sensing receptor gene associated with autosomal dominant familial isolated hypoparathyroidism (ADH). Treatment with subcutaneous recombinant human parathyroid hormone teriparatide (rhPTH [1-34]) 20 mcg twice daily for three days normalized her calcium and phosphorus concentrations.

CONCLUSION

rhPTH (1-34) is an effective treatment for patients with hypoparathyroidism due to gain-of-function mutations in the calcium-sensing receptor. ADH can be insidious in presentation and the diagnosis can be missed unless there is a high index of suspicion.