ESPE Abstracts

Background: Heterozygous inactivating mutations in the calcium sensing receptor (CaSR) gene cause mild hypercalcemia, normal to slightly elevated parathormone (PTH) levels and may vary from an asymptomatic clinical picture to a mild course. This clinical picture is also called familial hypercalcemic hypocalciuria. In this study, it is aimed to present two sibling cases due to CaSR mutation with interesting features.

Case 1: 12 year 3-month-old female was consulted for mild hypercalcemia while she was being followed up with a diagnosis of recurrent pancreatitis. No cause for recurrent pancreatitis was found. Her weight was 47.05 kg (0.21 SDS), height was 156.6 cm (0.53 SDS), and she had puberty Tanner Stage V. The lower and upper limit values of the laboratory tests during the follow-up were as follows; calcium 10.1-12 mg/dl, phosphorus 2.7-4.5 mg/dl, PTH 75.5-113.9 pg/ml, 25OHD 14.8-25.3 ng/ml, urine calcium/creatinine the ratio 0.02-0.21. No mutation was found in the serine protease inhibitor kazal type 1 and cystic fibrosis transmembrane conductance regulator genes, both genes can play a role for recurrent pancreatitis. A c.1583T>A (p.I528N) (heterozygous) mutation was detected in the CaSR gene. Cinacalcet 30 mg/day, 2x0.5 tablet (20.8 mg/m²/day) was started, because mutation was accepted as a pathogenic, and no pancreatitis attack was observed in the next 3.5-year follow-up.

Case 2: The patient, who was delivered via C/S at 25 weeks, 780 gram, was consulted at the age of 66 days due to low phosphorus when she was followed up in the intensive care unit. It was learned that she is sister of Case 1. The laboratory tests during the follow-up were as follows; calcium 9.9 mg/dl, phosphorus 1.48 mg/dl (3.7-4.3), PTH 1.2 pg/ml, 25OHD 35 ng/ml, ALP 1044 IU/L. Oral phosphorus solution was started in the neonatal period with the diagnosis of osteopenia of prematurity. However, while calcium values were normal, the same mutation was found in the CaSR gene, because her sister had this mutation. In the sixth month, the patient had calcium 12.2 mg/dl, phosphorus 4.6 mg/dl, PTH 143.2 pg/ml, 25OHD 21 μ/L, and then cinacalcet treatment was initiated.

Conclusions: It should be considered that CaSR mutations may cause recurrent pancreatitis, and the setting of hypercalcemia clinic may extend to the sixth month due to renal and tubular immaturity due to prematurity.