SAT-212 - Possible Primary Hyperparathyroidism with Hypercalcemia in Two Infants with Wolf Hirschhorn Syndrome

Background:

Wolf Hirschhorn Syndrome (WHS) is caused by 4p deletion with distinctive facial features, poor growth, intellectual disability, hypotonia, cardiac and renal defects. Rarely, hypercalcemia (hyperCa) is reported in WHS due to hyperparathyroidism (HPT).

Cases:

Case 1: female born small for gestation age (SGA) at 37 weeks with intrauterine growth restriction (IUGR) in pregnancy. She had hypertelorism, wide nasal bridge, downslanting eyes, low set ears, bilateral(B/L) echogenic kidneys, atrial septal defect (ASD), and pulmonary hypertension.

HyperCa was first detected on day of life (DOL) 7: serum calcium (Ca) 10.6 mg/dL (N 8.5-10.5 mg/dL). She was feeding Similac (Ca content 527 mg/L) and breastmilk (Ca content 200-300 mg/L) with human milk fortifier (HMF). HMF was discontinued due to high Ca content. Mild hyperCa persisted so at 4 weeks feeds were switched to Similac 60/40 (Ca content 379 mg/L). Lasix was started at 2 months (mo) for pulmonary over-circulation. At 3 mo, Ca 11.2 mg/dL, parathyroid hormone (PTH) 230 pg/mL (N 10-65 pg/mL), alkaline phosphatase (ALP) 690 U/L (N 109-357 U/L), with normal phosphorus (P), 25-Vitamin D (VitD), and magnesium. Fractional excretion of calcium (FECa) was > 0.01, ruling out familial hypercalciuric hypercalcemia (FHH). At age 3 mo she had nephrocalcinosis on ultrasound (US) hence was switched to Calcilo formula (Ca content 19.3 mg/L), and no VitD. US showed 3 mm hypoechoic nodule that can represent parathyroid gland. Until age 6 mo hyperCa and HPT persisted: calcium 10.2-11.7 mg/dL and PTH 107-202 pg/mL. However, at 7 mo Ca downtrended to 8.1 mg/dL, so Calcilo was decreased to 66% of feeds. At 8 mo, PTH uptrended to 523 pg/mL and 25-VitD was low 17 ng/mL (N30-100 ng/mL), so VitD was added. Her Ca and PTH remained stable on mix of Calcilo and Similac. At age 10 mo Ca 10.9 mg/dL, PTH 132 pg/mL, and 25-VitD trended up to 26.9 ng/mL.

Case 2: female born SGA at 37 weeks with pregnancy complicated by IUGR and hypothyroidism. She had hypertelorism, broad flat nasal bridge, small chin, downsloping palpebral fissures, B/L renal dysplasia, ASD, and ventricular septum defect. Initial Ca on DOL 6 was 10.8 mg/dL. At 3 weeks Ca 11.4 mg/dL, PTH 272 pg/mL, ALP 453 U/L with normal P, 25-VitD, 1,25 dihydroxyVitD, and thyroid tests. Her formula was first switched to Similac 60/40, then a mix of Similac 60/40 and Calcilo. US studies were negative for parathyroid nodule and nephrocalcinosis. Spot FECa > 0.01 ruled out FHH. At 2 mo age PTH 179 pg/mL, Ca 10.9 mg/dL, 25-VitD 28.8 ng/mL.


Results: Both babies had mild persistent hyperCa with likely primary HPT. Other etiologies like FHH, secondary HPT, immobilization, dehydration, acidosis, familial HPT, and medication were ruled out.


Conclusion: HyperCa and HPT can rarely occur in WHS. It may be due to primary HPT, but mechanism remains elusive. While treating hyperCa with low-Ca formulas, monitoring for hypocalcemia and VitD deficiency is essential.

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