Does Fasting and Postprandial Blood Sampling for Thyroid Evaluation Make a Difference in Children?

Abstract

BACKGROUND Thyroid function tests are one of the commonly undertaken investigations in any paediatric outpatient department. Based on the existing literature, there are no standard guidelines in respect of the sampling procedure to be followed in infants and children. Every paediatrician is aware of the logistic problems in taking a fasting sample in infants and younger children unlike adults. In this context, it was planned to undertake a pilot study to identify if the timing of sampling, fasting or postprandial status, makes any difference with respect to the thyroid function tests in children MATERIALS AND METHODS This was a descriptive study undertaken at the paediatric unit of Chengalpattu Medical College to evaluate if there is any difference between fasting and postprandial blood levels of Thyroid stimulating hormone and free T4 in children. The study was approved by the institutional ethical committee and informed written consent and assent obtained prior to study. Fifty one children between 1 and 12 years of age were recruited based on their willingness, from the endocrine clinic and the paediatric outpatient clinic. Fasting and postprandial blood samples were collected by venepuncture at 8 a.m. and 10.15 a.m. respectively. Blood samples were analysed using electrochemiluminescence method. Data analysis was done using Epi info software. RESULTS 51 children underwent fasting and postprandial sampling for thyroid evaluation. The results did not reveal any statistically significant difference between the fasting and postprandial samples for both TSH and Free T4. The same was true for both hypothyroid and euthyroid children. Subclinical hypothyroidism was encountered in one child in the fasting sample. CONCLUSION This pilot study revealed that postprandial TSH and Free T4 can be used as reliable test for thyroid evaluation as is a fasting sample in children.

Effect of satiety on TSH and free thyroxin levels in healthy individuals and patients with subclinical and overt hypothyroidism

“…Studies in the literature [6,7,[10][11][12][13][14][15][16][17] have shown that satiety causes a decrease in TSH in general, but this effect isn't seen in children [18]. In our study, the lowering effect of satiety on TSH was observed in all normal, subclinical hypothyroid and hypothyroid groups as in previous studies [6,14,15].…”

“…In many studies [6,11,[14][15][16]18], there was no significant effect of satiety on fT4 level while in our study it was determined that satiety can increase fT4 level only in the control group. But even this effect has small effect size.…”