Bone Abstracts

Background: Hypercalcemia in childhood is rare, can be of various origin and might go unrecognized until severe signs appear. We demonstrate hypercalcemia of different causes in two infants.

Case no 1.: 5-month old girl with failure to thrive, constipation, muscle hypotonia, dehydration, where total calcaemia peaked to 4.25 mmol/l. Low calcium diet, application of glucocorticoids and furosemide resulted in a drop in calcaemia to values below 3 mmol/l and in an overall clinical improvement within 2 weeks. Williams-Beuren syndrome (WBS), benign familial hypocalciuric hypercalcemia (FHH), neonatal severe primary hyperparathyroidism (NSHPT), Jansen’s metaphyseal dysplasia, primary hyperparathyroidism, vitamin D intoxication, granulomatous diseases, thyroid disease, malignancy were all ruled out. The diagnosis of idiopathic infantile hypercalcemia (IIH) was established. CYP24A1 inactivating mutation p.R396W+L409S (c.1186c>t)+(c.1226t>c) was later identified in this patient, thus confirming the diagnosis IIH. Currently the girl is 10-years-old, with normal anthropometric parameters and normal values of serum and urinary calcium.

Case No. 2: A 7-month old girl with normal perinatal history was referred due to lethargy, anorexia, failure to thrive, psychomotor retardation, muscle hypotonia. Blood biochemistry revealed high levels of serum calcium (S-Ca, 3.5 and 3.8 mmol/l respectively) with low parathyroid hormone (S-PTH) concentration (4.8 ng/l; normal 15–65), and otherwise normal lab results Echocardiography was normal, with no signs of aortal or pulmonary artery stenosis. A diagnosis of idiopathic infantile hypercalcaemia was first established and girl received intravenous corticosteroids and oral furosemide together with adequate hydration and low-calcium diet. This resulted in a drop in S-Ca (3.02 mmol/l) after 2 days of treatment. She then received a milk-free diet without vitamin D supplementation. Calcemia was in the range of 2.25–2.5 mmol/l. Her psychomotor development and muscle hypotonia have been improving very slowly in comparison with the drop in S-Ca and her weight gains were inappropriately low. She had no striking dysmorphic features, however, the persisting psychomotor retardation and failure to thrive prompted us to have FISH (fluorescent in situhybridization) performed. The FISH revealed deletion at the long arm of chromosome 7, thus arriving at the diagnosis of WBS. Currently, the girl is 6 years old, mildly retarded, being followed up in our ward. Typical facial features of WBS have since evolved.

Conclusion: Disturbances of calcium homeostasis have to be considered in the differential diagnosis of various disease states., especially in infants with failure to thrive.

Disclosure: The authors declared no competing interests.