ESPE Abstracts

Background: Hypercalcemia requires new investigation pathways after publishing the mutations of the CYP24A1 gene. Furthermore, diagnostic puzzles connected to it still remain.

Objective and hypotheses: We present a 1.5-years-old girl with infantile hypercalciuria who has been followed-up since she was 4 months old. The child is born from uneventful pregnancy, normal delivery, on term with weight 3600 g and length 52 cm. Two months after birth she became irritable, with decreased appetite, several episodes of blood in the stools and slow weight gain. The urine analysis showed erythrocyturia and leucocyturia.

Method: After admission in hospital a bilateral nephrocalcinosis was revealed accompanied by hypercalciuria (Ca/creatinine 1.37 (<0.20), hypercalcemia (total Ca 3.65 mmol/l (2.08–2.65), iCa 1.70 mmol/l (1.13–1.32), suppressed PTH (<3.00 pmol/l) and elevated 25-hydroxyvitamin D3 > 70 ng/ml. A PTH-independent hypercalcemia was diagnosed. There was no history of familial hypercalcemia, subcutaneous fat necrosis or vitamin D intoxication. No syndromic or dysmorphic features were found. Partial improvement was registered after conventional treatment. After introducing bisphosphonates (Pamidronate) infusions in 2 consecutive days the clinical symptoms gradually resolved and calcium levels became stabile around the upper limit of the norm – total Ca 2.73 mmol/l, iCa 1.29 mmol/l.

Results: In the context of the new etiological causes a defect in 24-hydroxylase activity was suspected. A molecular genetic testing for mutation in the CYP24A1 gene was done in a referent center but showed negative results. Looking back to our investigations lower phosphate serum levels of 1.0 mmol/l at presentation were noticed to be present too. During the follow-up the phosphate levels slowly increased up to the lower limits of 1.6 mmol/l with TmP/GFR of 1.32, calcium levels are still on the upper limits and there is no significant progression of the nephrocalcinosis and no impairment of the renal function.

Conclusion: Infantile hypercalcemia still remains a diagnostic and therapeutic enigma.