Prevalence and factors associated with hypothyroidism among children aged 1-19 years with nephrotic syndrome attending Mulago paediatrics renal clinic

Abstract

Background: Hypothyroidism is a condition characterized by low levels of circulating thyroid hormones in blood. It is critical among children and adolescents because it affects their physical growth and intellectual development. Nephrotic syndrome is one of the commonest kidney diseases of children. It is characterized by leakage of protein from blood into urine, edema and/or hypoalbuminemia. Due to the heavy proteinuria, thyroid hormones and thyroglobulin are also lost in the urine. Furthermore, steroids that are used to treat children with nephrotic syndrome also reduce the release of thyroid stimulating hormone to some extent. Abnormal thyroid function in nephrotic syndrome has been reported in studies with hypothyroidism as the commonest form. The prevalence of hypothyroidism and associated factors among children and adolescents with nephrotic syndrome had not been studied yet increasingly more children were being treated for NS. Objective: To determine the prevalence and factors associated with hypothyroidism among children and adolescents aged 1 to 19 years with nephrotic syndrome attending the paediatric renal clinic in Mulago hospital. Methods: A cross-sectional design was used to study 70 children and adolescents aged 1 -19 years diagnosed with nephrotic syndrome and being followed up in the renal clinic in Mulago hospital. Data was collected with the aid of a structured questionnaire that was administered after seeking written informed consent from guardians or parents, assent from the children 8 -17 years and consent from 18 and 19 year olds. A blood sample was taken for analysis for thyroid stimulating hormone (TSH) and free thyroxine (T4), renal function tests and serum albumin. Urine samples were taken from participants for a dipstick. The data collected was entered into a password protected computer using Epi data 3.1 and analyzed using STATA version 14. Hypothyroidism was defined as a TSH level >10 mU/L and/ or free T4 below the lower limit of normal that is, FT4 <0.8ng/dL (10pmol/L) and those with TSH ranging between 4.5 and10 mU/L with normal age appropriate free T4 levels. Multivariable analysis using logistic regression models was utilized to determine the factors associated with hypothyroidism. A p-value< 0.05 was considered as significant. Results: We enrolled 70 participants with a mean age (standard deviation) of 9 years (3.8). There were more males; 36 of 70 (51.4%). The prevalence of hypothyroidism was 23% (16 out of 70 participants). Of the 16 children with hypothyroidism, 3 (18.7%) had overt hypothyroidism while the rest had subclinical hypothyroidism. Only low serum albumin aOR 54.17 (confidence interval 10.75-272.76 and a p value of 0.00) was associated with hypothyroidism. . The children and adolescents with no hypothyroidism had a higher average serum albumin of 3.9±0.11g/dL while those with hypothyroidism had a lower average of 1.8±0.18g/dL. Conclusion: The prevalence of hypothyroidism among children and adolescent with nephrotic syndrome attending Mulago Hospital paediatric renal clinic was 23%. Hypalbuminemia was the only factor that was found to be associated with hypothyroidism. Recommendation: children and adolescents that have NS with hypoalbuminemia should be screened for hypothyroidism. KEY WORDS: hypothyroidism, nephrotic syndrome, hypoalbuminemia