Case Quiz (December 2016)

A male infant, the second in order, of healthy parents was born at 32 weeks of gestation. Birth weight was 1740 g. Apgar score was 6 at 1 and 7 at 5 min. The baby was immediately intubated at birth because of respiratory distress and ventilation was provided during the 1st day of life. After surfactant therapy, he was extubated on the 4th day, but still needed 50% oxygen to obtain saturations above 85% without clinical signs of respiratory distress.On day 4 a cardiac murmur became audible. Echocardiography showed a complex cyanotic congenital heart disease (double outlet right ventricle, infundibular pulmonary stenosis, transposition of the great arteries and PDA with hypoperfusion of pulmonary arteries). Hence PGE1 was started at a dose of 0.1 ug/kg/min. A few hours after initiation of therapy, the patient needed intubation and ventilation because of apnoea. Within 24 h of PGE1 infusion, severe hyponatraemia (115 meq/l) along with polyuria (8 ml/kg/h) developed. The patient was supplemented with high doses of NaCl, up to 70 meq sodium/day. After that, PGE1 was maintained at a dose of 0.06 ug/kg/min. On day 12, serum Na was 124 mq/l and urine output was 7 ml/kg/h. On day 15, serum Na was 142 mq/l but urine output remained high 6-7 ml/kg/h. In the next few days, progressive decrease in the need for sodium supplementation was documented, suggesting a possible maturation mechanism. Plasma creatinine remained in the normal range throughout therapy but modest hypokalemia was observed along with polyuria.

Case Answer (December 2016)

Pseudo-Bartter syndrome due to use of PGE1.
Primary Bartter syndrome is associated with endogenous increased levels of prostaglandins. Well-known side-effects of PGE 1 infusions in the neonate are fever, apnoea, bradycardia, hypo- tension, seizures, diarrhoea, hyperostosis and oedema. Iatrogenic pseudo-Bartter syndrome may be caused by administration of PGE1.

Exogenous PGE 1 administration induced the same effect by increased renal PG levels, like in Bartter syndrome, causing natriuresis and polyuria in our patient. Severe hypokalaemia or acidosis were most likely avoided due to the aggressive medical treatment. Since not all patients on PGE 1 therapy develop polyuria and natriuresis, immaturity, genetic background and dosage were most likely involved in the phenotypic presentation of iatrogenic pseudo-Bartter syndrome in this preterm infant.