ASSOCIATION BETWEEN VARIOUS PERINATAL FACTORS AND CORD BLOOD TSH LEVEL VARIATIONS IN NEWBORNS

Abstract

BACKGROUND:

Thyroid hormones are important regulators of fetal neurodevelopment and are critical for brain development. The hormones released by the thyroid gland are Tri-iodothyronine [T3] and Tetra-iodothyronine [T4] which is under the control of thyroid stimulating hormone [TSH] released from the pituitary gland. This hormone is in turn under the control of thyrotropin releasing hormone [TRH] from hypothalamus. Congenital Hypothyroidism (CH) is inadequate thyroid hormone production in the newborn infants and is one of the most common preventable causes of mental retardation. Thus early detection and treatment of congenital hypothyroidism (CH) prevents intellectual disability and optimises growth and developmental outcomes. Indian Academy of Paediatrics recommends the use of cord blood samples for screening for congenital hypothyroidism Different researchers have used different cut offs for cord blood TSH levels. A value of > 20 mIU/ml for recall of retesting and neonates who have cord blood TSH values >20 mIU/ml were advised free T3, T4, TSH assessment after 3 days of life. Various maternal and perinatal factors have been found to affect cord blood thyroid hormone levels, particularly cord blood TSH. A study of the influence of these factors is therefore necessary to improve the interpretation of screening data. This could result in lower recall rates and lessen the anguish of parents awaiting the diagnosis.

MATERIALS AND METHODS:

This prospective cross sectional study was conducted in the Department of Obstetrics & Gynecology, MIMER Medical College and BSTR hospital, Talegaon Dabhade for duration of 1 year 6 months. All ‌parturients‌ ‌coming to the labour ward were included in this study‌. Women‌ ‌not‌ ‌willing‌ ‌to‌ ‌participate‌ ‌in‌ ‌the‌ ‌study‌ and neonates with major congenital anomalies were excluded. A total of 960 neonates were studied, out of which 98 had high CBTSH levels ≥ 20 mlU/L. The effect of perinatal variables on cord blood TSH was analysed statistically. All the data was entered in Microsoft Excel sheet and then transferred to SPSS software version 18 for statistical analysis. Appropriate tests were applied according to type and distribution of data and differences were regarded as significant at values of p < 0.05.

RESULTS :

The mean cord blood TSH level was 11.91 ± 7.2 mIU/L with 10.2% of neonates having high cord blood TSH levels > 20 mIU/L. Significant association was found between the perinatal factor like parity with high cord blood TSH levels (p <0.05). No significant association was found between high CBTSH levels and gestational age, maternal age, premature rupture of membranes, induction of labour, gender of the baby or antenatal complications like preeclampsia, gestational diabetes mellitus or anaemia.

CONCLUSION:

Parity was found to be significant perinatal factors associated with high cord blood TSH values. Hence, cord blood TSH values should be interpreted in the light of these perinatal variables.

Keywords: Cord blood Thyroid stimulating hormone, perinatal factors, congenital hypothyroidism.