Neonatal hyperbilirubinemia and its association with thyroid hormone levels and urinary iodine excretion.
OBJECTIVE
To investigate, if, urinary iodine contents as a marker of iodine deficiency and hypothyroidism are associated with the incidence of neonatal hyperbilirubinemia.


METHODS
One hundred neonates with total serum bilirubin > or = 15 mg/dl and with no known cause of jaundice were included in the study as a jaundice group. An equal number (n = 100) of non-jaundiced neonates (bilirubin < or = 14.9 mg/dl) with matching for age, gestation period and weight were enrolled in the study as a control group.


RESULTS
Thirteen neonates (13%) in the study group had urinary iodine levels < 100 mg/dl as against only 2 (2%) in the control group (p < 0.05). Thirty-four (34/200-17%) neonates i.e. 17 each in the study and control groups had serum TSH > 5 mU/ml and hence an indirect indicator of iodine deficiency in the study population. The mean serum levels of total T3, T4 and TSH in the study neonates were 1.52 +/- 1.23 ng/ml, 15.8 +/- 12.0 micrograms/dl & 3.13 +/- 3.0 mU/ml respectively and did not differ significantly from the mean levels in the control group. Only one neonate in the study group had serum TSH > 20 mU/ml which was suggestive of hypothyroidism, but had normal T3 & T4. Seven neonates in the study group and 8 in the control group had low T4. There was no significant correlation between the maternal and neonatal urine iodine levels, thyroid functions and the bilirubin levels (p > 0.01).


CONCLUSIONS
The jaundiced babies had lower urine oidine levels than the control population. Since, there was no significant difference in the levels of the thyroid hormones, no cause and effect relationship could be inferred between iodine deficiency and jaundice.
Singh
B
B
Departments of Pediatrics (Division of Neonatology), and Nuclear Medicine, PGIMER, Chandigarh, India.
Ezhilarasan
R
R
Kumar
P
P
Narang
A
A
D001663:Bilirubin / Q000097:blood; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001724:Birth Weight; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000453:epidemiology*; D015994:Incidence; D007194:India / Q000453:epidemiology; D007231:Infant, Newborn; D007455:Iodine / Q000652:urine*; D007567:Jaundice, Neonatal / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy / Q000652:urine; D008297:Male; D010789:Phototherapy / Q000706:statistics & numerical data; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000453:epidemiology*; D012016:Reference Values; D013963:Thyroid Hormones / Q000097:blood*
D015415:Biomarkers; D013963:Thyroid Hormones; D007455:Iodine; D001663:Bilirubin