Cord Blood Thyroid Stimulating Hormone Values in Healthy Term Babies delivered at Abubakar Tafawa Balewa University Teaching Hospital Bauchi, Northeastern Nigeria.

Background: Congenital hypothyroidism is one of the most common preventable causes of mental retardation and clinical manifestations are often subtle or absent at birth and hence the need for screening. Implementation of newborn screening requires local normative values.

Objectives: To determine the normative values of cord Thyroid Stimulating Hormone (TSH) among term babies in Bauchi, Northeast Nigeria and compare it with that from other centers in Nigeria.

Methodology: Cord blood samples from 200 term babies were analyzed for TSH by Fluorescence Immunoassay technique in this descriptive cross-sectional study. A cut-off of >20 µIU/ml was used for recall. The mean and range were determined and compared with those of previous local studies using t-test. Impact of some maternal and infant factors on TSH was also assessed.

Results: The overall mean (SD) cord TSH was 3.74 (±1.99) µIU/ ml and the range was 0.73 to 15.22 µIU/ml (2.5th to 97.5th centile) and none had TSH > 20 µIU/ml and hence our recall rate was 0%. The mean cord TSH was comparable to that reported by a lone local multicenter study (p = 0.120) but significantly different from that of 3 other local studies (p < 0.001). There was also no significant difference between the means of different gender, birth weight groups, mode of delivery, socio-economic classes, maternal age and parity.

Conclusion: The Cord blood TSH level of most term newborn in Bauchi, similar to other Nigerian studies, is < 10 µIU/ml with a few but significant percentage recording cord TSH level > 10 µIU/ml. Gender, birth weight, mode of delivery, socio-economic class, maternal age and parity were not significantly related to cord TSH level. The mean blood TSH values from different studies across the country tend to vary based on the assay technique. We recommend a nationwide multicenter study with a much larger sample size, lower cutoff value for recall and a unified sample processing laboratory if national normative values are to be developed.