I was once called for a referral. A few days old preterm baby having seizures that occurred within the first few hours of life. Baby was having seizures despite the anti-convulsant that was already given. The baby was already referred to a neurologist before I stepped into the picture. Baby was worked up and his electrolytes showed low sodium (112). (The normal level is 135 – 145; if the value is lower than 135, that’s considered hyponatremia. If value is less than 125, baby can have seizure that will not be controlled by anticonvulsant until the problem is corrected). In this case, it seems the most likely cause of seizure was identified. Thus, the immediate thing for me to do was to correct this abnormality and hope that it will eventually stop the seizures.
So after 48 hours, the sodium level was already raised to near normal. The good thing was, seizure already stopped. So I guess the baby’s urgent problem was resolved.
The question that bothered us was, why did the baby have severe hyponatremia? It is a rule of thumb that the electrolyte picture of a baby within 48hrs from birth generally reflects that of the mother. Unless that baby also has a congenital abnormality such as in cases of congenital adrenal hyperplasia (CAH). The baby in this case did not have physical signs highly suggestive of CAH, and the newborn screening eventually was normal, so this as the cause was easily ruled out. So, this made me then thought of the mother’s electrolyte status.
I interviewed the mother when she visited her baby at the NICU. I asked her if she was on prolonged intravenous fluid administration, if she was taking medications. She revealed she was on prolonged furosemide “maintenance.” This was given by an internist she consulted. BINGO! Seems I nailed the culprit with mere few questions. So I went on further with my interview. I asked why was she on prolonged furosemide intake. She said, she consulted the internist because she had edema (swelling) of both her lower legs. I further asked, “at what months of pregnancy did she notice the onset of edema, of hypertension. She did not know she was pregnant then when she had that consultation. Then my next question was, “is your menstrual cycle irregular?” And she replied YES! I was then flabbergasted and felt sorry for the mother, most especially for the baby. Why?
Let me reconstruct the story for a clearer understanding. Here was a woman with irregular menstrual cycle. She became pregnant but was not able to realize it because of her irregular schedule. Then later in the pregnancy, she developed edema of both lower extremities. She consulted an internist because of the latter, who also incidentally discovered she was hypertensive. The internist did not know the patient was pregnant; he did not do pregnancy test nor abdominal ultrasound. Pregnancy was remote from his consideration, thus he did not do these tesst… even if the woman was already showing signs of PREECLAMPSIA. So he gave furosemide. But since the edema was unresolving, she kept on taking the drugs. Few days ago, she was having abdominal pain. She saw another doctor, an OB-Gyn, who requested for an ultrasound. HALLELUJAH of all hallelujahs, she was indeed PREGNANT. And since her blood pressure remained uncontrolled, she was scheduled for emergency CS delivery. Since she was on prolonged furosemide intake, aside from it removing water from the body, furosemide also eliminates electrolytes like sodium and potassium. Since she was already hyponatremic, so was also the baby whose blood supply comes from the mother via the placenta.
The rest of the baby’s course in the neonatal ICU was unremarkable thus I signed out from the service after making sure baby was ready for discharge.