Normative Data for Thyroid Stimulating Hormone for Screening of Congenital Hypothyroidism
To generate normative data for thyroid stimulating hormone (TSH) levels in heel prick samples collected from newborns from 24 h to 7 d of age.
Five regional laboratories were designated as the testing laboratories. Dried blood spots (DBS) from babies (> or = 34 wk of gestation) were collected by heel prick at least after 24 h and within seven days after birth. TSH estimation was done using time resolved fluoroimmunoassay. Values above 20mIU/L were labelled as presumptive positive. Hour interval specific normative data was categorized at 6 h intervals. Another category placed was division into 24–72 h category, 73–96 h and 99–168 h. Percentile charts were calculated across these specified intervals.
Samples analysed were 104,006 collected cumulatively from the 5 centers. Of the total samples analysed for TSH, 92.8% had values less than 5 mIU/l. When TSH values were interpreted with respect to time, a steady decrease with time was observed. Of the babies' samples, 48,839 were collected between 24 and 48 h, 23,983 between 49 to 72 h and 30,883 were collected after 72 h. The mean TSH concentration demonstrated a steady decline from 24 h to 168 h. It is apparent that 10 mIU/l is the 97.5th percentile value even when corrected for gender, birth weight and age at sampling. Thus 10 mIU/l seems to be the right cutoff beyond which a second sample should be sought.
This is the largest series reported with a broader population mix with representations of both urban (including slums) as well as a rural population. As this study excluded preterm babies, the utility of cut offs generated is not applicable to this subset and also to critically sick neonates. However, this study gives a true representation of the normative values for majority of the newborns born at term with weight appropriate for the gestation.
KeywordsNewborn screening TSH Normative values
Writing Group: Dr. Seema Kapoor, Dr. Madhulika Kabra, Dr. Mani Kalavani, Dr. Roli Mathur.
Steering Group: Late Dr. SS Aggarwal (Chairperson), Dr. I C Verma, Dr. Veena Kalra, Dr. Vasantha Muthuswamy and Dr. Vijay Kumar.
AIIMS, New Delhi: Dr. Vinod Paul, Dr. Ashok Deorari, Dr. Sheffali Gulati, Dr. Ramesh Agarwal, Dr. Vandana Jain, Dr. Suman Vashishst, Dr. Suneeta Mittal;
MAMC, Delhi: Dr. AP Dubey, Dr. Siddharth Ramji, Dr. Sangeeta Yadav, Dr. Swaraj Batra, Dr. Sangeeta Gupta;
KEM Hospital Mumbai: Dr. Keya Lahiri, Dr. Ruchi Nanavati;
MEDISCAN Chennai: Dr. Sujatha Jagadeesh, Dr. Sudha Rathna Prabhu, Dr. K Saraswathi, Dr. Rathna Kumari;
IPGMER, Kolkata: Dr. Mitali Chatterjee, Dr. S. C. Biswas, Dr. Indranil Chakraborty, Dr. Tapas Som, Meena Jaishankar, Dr. Satinath Mukhopadhyay; Sandor, Hyderabad: Dr. A. I Dherai and Dr. Srimannarayana Rao;
NIMHANS Bangalore: Dr. D. Nagaraja.
ARRD, MK, SK, MM, AS, SS: regional centres collected, analyzed the data and participated in patient care; RMP: data coordination of the study; RM: overall coordination of the study; PKN: quality assurance; RC: laboratory tests; SK, MK, RM, KM, RMP: wrote the manuscript; SK and ARRD will act as guarantor of the paper.
Compliance with Ethical Standards
Conflict of Interest
Source of Funding
Indian Council of Medical Research.
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