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Indian Pediatr 2015;52: 435-436 |
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Congenital Hypothyroidism Screening with
Umbilical Cord Blood: Retrospective Analysis
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*MR Anand, Preetha Ramesh and Divia Nath
Department of Neonatology, Malabar Institute of Medical
Sciences, Calicut, Kerala, India. *[email protected]
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Incidence of congenital
hypothyroidism varies across countries and different geographic regions.
A retrospective analysis of cord blood thyroid stimulating hormone
values, and their subsequent follow-up, was done in a tertiary-care
center in Kerala, India. Congenital hypothyroidism was found at the rate
of 1 in 244, which is higher than reported incidence from other centers.
Keywords: Congenital hypothyroidism,
Incidence, Goiter.
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Congenital hypothyroidism has a worldwide incidence
of 1 in 4000. A higher incidence has been reported from India [1]. The
objective of our study was to ascertain the incidence of congenital
hypothyroidism in South Malabar area.
Our study was conducted in a tertiary care hospital
in Calicut, Kerala. We conducted a retrospective analysis of umbilical
cord thyroid stimulating hormone (TSH) values. All inborn deliveries –
from October 2012 to October 2013 – in a tertiary care hospital in
Calicut, Kerala, were included. TSH, FT4 and FT3 were assayed by
chemiluminiscent immunoassay method. A mixed cord blood sample obtained
soon after birth was sent immediately for assay TSH. All cord blood TSH
values of more than 10 mU/L were followed up at 72 hours of age with a
repeat TSH estimation. Those babies with a rising trend in TSH were
evaluated with TSH, FT4 and FT3 on day 5 of life. Subsequent follow up
was done at 2 weeks of age in individual cases. Congenital
hypothyroidism was diagnosed if TSH on day 5 was >40 mU/L with a low FT4
or if at 2 weeks of age the TSH >10 mU/L with low FT4 [2]. Radio nuclear
scanning was not done in all cases prior to treatment. Data retrieved
from electronic medical records were analyzed by SPSS version 16.
We excluded 120 cases from the analysis, which
included perinatal deaths, those lacking adequate follow ups, and those
where a proper cord blood sample could not be obtained. Total numbers of
samples included in the analysis were 1950 (1268 female) out of which
1551 were term and 397, preterm. Median cord blood TSH value was 6.5 mU/L.
Based on our policy of rescreening those with a cord TSH of >10 mU/L,
403 babies needed rescreening at 72 hours. Upon rescreening at 72 hrs,
41 babies had a rising trend in TSH. Out of these 41 cases, eight cases
were diagnosed to have hypothyroidism on follow-up; six on day 5 and two
on day 14. Cord blood TSH values and the number of hypothyroidism cases
within each group are provided in Table I. Congenital
hypothyroidism was diagnosed in 8 cases.
TABLE I Distribution of Hypothyroidism Cases According to Cord Blood Tsh Levels
Cord blood TSH (mU/L) |
No. |
Hypothyroidism cases |
>100 |
3 |
3 |
90 -100 |
1 |
0 |
60-70 |
1 |
1 |
50-60 |
4 |
0
|
40-50 |
4 |
0 |
30-40 |
13 |
1 |
20-30 |
43 |
2 |
10-20 |
334 |
1 |
<10 |
1549 |
0 |
Cord blood TSH was >20 mU/L in all samples, except
one where it was 18 mU/L. One baby showed a goiter in radionuclide
scanning, whereas maternal hypothyroidism was present in two infants,
and maternal hyperthyroidism in one child. No specific cause was found
in the other five babies.
A cord blood cut-off of 20 mU/L is considered
reasonable but it might be prudent to rescreen babies with a cord blood
TSH above 10, as one of our patients had a cord blood TSH of 18 mU/L.
Taking a cord blood TSH of 10 mU/L as cut off, our false positivity was
20%. Results from this study population show a higher incidence of
congenital hypothyroidism than that has been reported from other
countries [3-5] or from other parts of India [1,6,7]. Increase in
incidence within the same country over subsequent years also has been
reported [8]. The incidence of primary hypothyroidism vary depending on
dietary iodine sufficiency, laboratory methods of screening, different
test cut-off values, and demographic, geographic, racial and ethnic
factors. Social customs like consanguinity also alter the incidence [9].
Transient hypothyroidism also may contribute to varying prevalence [4].
Cord blood TSH provides a suitable first line diagnosis congenital
hypothyroidism, especially when a 72-hour screen cannot be ensured. This
study has limitations of being a hospital-based retrospective study. In
view of higher incidence reported here, prospective studies on a larger
population are needed to confirm the findings and elucidate the reasons
for the increased incidence.
Contributors: AMR: conceived and designed
the study, data collection and analysis, and manuscript preparation. He
will act as the guarantor; PR and DN: data collection and preparation of
the manuscript. The final version was approved by all authors.
Funding: None; Competing interests: None
stated.
References
1. Sanghvi U, Diwakar KK. Universal screening for
congenital hypothyroidism. Indian Pediatr. 2008;45:331-2.
2. Bhatia V. Congenital hypothyroidism is not always
permanent: caveats to newborn thyroid screen interpretation. Indian
Pediatr. 2010;47:753-54.
3. Wu LL, Sazali BS, Adeep N, Khalid BA. Congenital
hypothyroid screening using cord blood TSH. Singapore Med J.
1999;40:23-6.
4. Nascimento ML, Silva PC, Simoni G, Lobo GS, Souza
CD. Congenital hypothyroidism screening programme preliminary results. J
Pediatric (Rio J). 1997;73:176-9.
5. Ordookhani A, Mirmiran P, Najafi R, Hedayati M,
Azizi F. Congenital hypothyroidism in Iran. Indian J Pediatr.
2003;70:625-8.
6. Kaur G, Srivastav J, Jain S, Chawla D, Chavan BS,
Atwal R, et al. Preliminary report on neonatal screening
for congenital hypothyroidism, congenital adrenal hyperplasia and
glucose-6-phosphate dehydrogenase deficiency: a Chandigarh
experience. Indian J Pediatr. 2010;77:969-73.
7. Manglik AK, Chatterjee N, Ghosh G. Umbilical cord
blood TSH levels in term neonates: a screening tool for congenital
hypothyroidism. Indian Pediatr. 2005;42:1029-32.
8. Dilli D, Çzbaº , Acican D, Yamak N, Ertek M,
Dilmen U. Establishment and development of a national newborn screening
programme for congenital hypothyroidism in Turkey. J Clin Res Pediatr
Endocrinol. 2013;5:73-9.
9. Desai MP. Congenital hypothyroidism: screening dilemma. Indian J
Endocrinol Metab. 2012;16:153-5.
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