Increased parathyroid hormone and decreased calcitriol during neonatal extracorporeal membrane oxygenation

We noted that age-related normal calcium doses in neonates on venoarterial extracorporeal membrane oxygenation result in hypercalcemia. To avoid hypercalcemia and its potential consequences these infants are given one-half the normal calcium dose. We studied the pathogenesis of hypercalcemia and hypomagnesemia by evaluating calcitriol, intact parathyroid hormone, and calcitonin status during extracorporeal membrane oxygenation.

Prospective, observational study in the intensive care unit of a 225-bed tertiary care pediatric hospital.

Twelve neonates under 7 days old with severe pulmonary disease requiring extracorporeal membrane oxygenation.

Blood was obtained for intact parathyroid hormone and calcitriol concentrations before cannulation, during (extracorporeal membrane oxygenation days 2, 4, and predecannulation in those on >6 days), and after decannulation on days 1 and 3. Calcitonin concentrations were measured before cannulation, during, and after decannulation in the last seven patients. Prior to cannulation parathyroid hormone was normal (1.4-5.7 pmol/l) and on day 2 increased to 7.8+/-8.4 pmol/l. Before cannulation calcitriol was 14.5+/-8.21 pmol/l (normal 41-143 pmol/l), and concentrations remained low until after decannulation. In three of the seven infants calcitonin concentrations (normal <73 ng/l) were above the upper limit of the assay (>1150 ng/l) prior to cannulation and during extracorporeal membrane oxygenation.

Regulation of the vitamin D-endocrine system during neonatal venoarterial extracorporeal membrane oxygenation appears to be aberrant compared to normal vitamin D-endocrine system regulation. The pathogenesis of this abnormality remains unclear and requires further study.