Thyroid Dysfunction in Children with Idiopathic Nephrotic Syndrome Attending a Paediatric Hospital in Qazvin, Iran

Hypothyroidism among Children with Nephrotic Syndrome Admitted to a Tertiary Care Centre

Introduction

Nephrotic syndrome is a glomerular disease characterized by massive urinary protein loss occurring in children. Proteinuria also leads to loss of thyroid binding globulin affecting thyroid function. This study aimed to find out the prevalence of hypothyroidism among children with nephrotic syndrome admitted to a tertiary care centre.

Methods

A descriptive cross-sectional study was conducted among children with nephrotic syndrome admitted to a tertiary care centre from 06 July 2020 to 06 June 2021 after obtaining ethical approval from the Ethical Review Committee. They were tested for free T3, free T4 and TSH. A convenience sampling method was used. The point estimate was calculated at a 90% Confidence Interval.

Results

Among 69 children with nephrotic syndrome, the prevalence of hypothyroidism was 49 (71.01%) (62.03-80.00, 90% Confidence Interval).

Conclusions

The prevalence of hypothyroidism among children with nephrotic syndrome was higher than other studies done in similar settings.

Keywords

children; hypothyroidism; nephrotic syndrome; prevalence.

Hypothyroidism among children and adolescents with nephrotic syndrome in Mulago National Referral Hospital, Kampala, Uganda; a cross-sectional study

BACKGROUND

Nephrotic syndrome (NS) is the commonest glomerular disease among children. It is characterized by heavy proteinuria and is a risk factor for hypothyroidism in the affected children. Hypothyroidism is of concern because it affects the physical and intellectual development of children and adolescents. This study sought to establish the prevalence and factors associated with hypothyroidism among children and adolescents with NS.

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 kidney clinic in Mulago National Referral Hospital. Questionnaires were used to collect patients' socio-demographics and clinical information. A blood sample was taken for analysis for thyroid stimulating hormone (TSH) and free thyroxine (FT4), renal function tests and serum albumin. Hypothyroidism included both overt and subclinical forms. Overt hypothyroidism was defined as TSH level > 10 mU/L and FT4 < 10pmol/L, or FT4 < 10pmol/l with normal TSH, or TSH < 0.5mU/l. Sub-clinical hypothyroidism was defined as TSH ranging between 5 and10 mU/L with normal age appropriate FT4 levels. Urine samples were collected and taken for a dipstick examination. The data was analyzed using STATA version 14. The Bayesian Logistic regression analysis approach was used to estimate odds ratios (OR) and their associated 95% credible intervals. All predictor variables with p value < 0.05 at frequentist statistical analysis were considered significant.

RESULTS

The mean age (standard deviation) of participants was 9 years (3.8). There were more males; 36 of 70 (51.4%). The prevalence of hypothyroidism was 23% (16/70 participants). Of the 16 children with hypothyroidism, 3 (18.7%) had overt hypothyroidism while 13 had subclinical hypothyroidism. Only low serum albumin was found to be strongly associated with hypothyroidism; Bayesian OR 132.57 (CI 9.13-567.10) with a frequentist OR of 37 and a p value of 0.001.

CONCLUSION

The prevalence of hypothyroidism among children and adolescent with nephrotic syndrome attending Mulago Hospital paediatric kidney clinic was 23%. Hypoalbuminemia was found to be associated with hypothyroidism. Therefore, children and adolescents that have severely low levels of serum albumin should be screened for hypothyroidism and linked to endocrinologists for care.

Overt Hypothyroidism and Severe Growth Retardation in a Preschool Girl with Poorly Controlled Nephrotic Syndrome: Case Report and Literature Review

Background

Nephrotic children may develop thyroid hormone dysfunction due to urinary excretion of thyroid hormones. In contrast to the subclinical hypothyroidism that affects around 30% of children with nephrotic syndrome (NS), the patient in this case had overt hypothyroidism and severe growth retardation.

Clinical case

A 5 years and 8 months old girl with steroid-dependent NS was referred from another center due to persistent edema and decreased diuresis, being treated with mycophenolate mofetil (MMF) 250 mg once a day and L-thyroxine 50 mcg daily since 4 months of NS onset because of hypothyroidism. Her albumin was 12.64 g/l, cholesterol 25.64 mmol/l and proteinuria 5 g/l. Severe growth retardation was observed: patient's height was 93.5 cm (-13 cm <3 percentile), weighted 17.2 kg (15-25 percentile). Her disease vintage was over 3 years. Girl's growth velocity has slowed down from 3.5 months. The patient received a high cumulative dose of prednisolone (approx. 7800 mg in 1 year and 8 months). Thyroid-stimulating hormone was higher (18.04 mU/L) with reduced FT4 11.43 pmol/l and IGF-1 < 15 µg/L. Kidney biopsy revealed minimal change disease, and genetic testing was negative. Intensive NS treatment with methylprednisolone pulse therapy, enlarged doses of MMF and albumin infusion were started and L-thyroxine dose was increased to 75 mcg. TPOAb was in normal range (12.65 IU/ml). After 3 weeks she was discharged with no edema and after stopping methylprednisolone treatment thyroid function normalized and L-thyroxin was discontinued. Two weeks later standard growth hormone stimulation test with clonidine showed partially insufficient growth hormone secretion. During NS remission with normalization of thyroid function (TSH 6.680 mU/l, FT4 13.85 pmol/l) and normalization of IGF-1 level (132 mcg/l) partial catch-up growth was observed (height velocity increased from 3.5 cm/year to 7.3 cm/year, based on 4-month calculation period).

Conclusions

Clinicians should be aware of a risk of developing hypothyroidism and consider thyroid function testing during the treatment of children with NS, as well as actively treat hypothyroidism and evaluate growth.

Hypothyroidism Among Children and Adolescents With Nephrotic Syndrome in Mulago National Referral Hospital, Kampala, Uganda; a Cross-sectional Study

Background

Nephrotic syndrome (NS) is the commonest glomerular disease among children. It is characterized by heavy proteinuria and is a risk factor for hypothyroidism in the affected children. Hypothyroidism is of concern because it affects the physical and intellectual development of children and adolescents. This study sought to establish the prevalence and factors associated with hypothyroidism among children and adolescents with NS.

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 kidney clinic in Mulago National Referral Hospital. Questionnaires were used to collect patients' socio-demographics and clinical information. A blood sample was taken for analysis for thyroid stimulating hormone (TSH) and free thyroxine (FT4), renal function tests and serum albumin. Hypothyroidism included both overt and subclinical forms. Overt hypothyroidism was defined as TSH level > 10 mU/L and FT4 < 10pmol/L, or FT4 < 10pmol/l with normal TSH, or TSH < 0.5mU/l. Sub-clinical hypothyroidism was defined as TSH ranging between 5 and10 mU/L with normal age appropriate FT4 levels. Urine samples were collected and taken for a dipstick examination. The data was analyzed using STATA version 14 and a p-value < 0.05 was considered as significant.

Results

The mean age (standard deviation) of participants was 9 years (3.8). There were more males; 36 of 70 (51.4%). The prevalence of hypothyroidism was 23% (16/70 participants). Of the 16 children with hypothyroidism, 3 (18.7%) had overt hypothyroidism while 13 had subclinical hypothyroidism. Only low serum albumin, aOR 35.80 (confidence interval 5.97-214.69 and a p value of < 0.001) was associated with hypothyroidism.

Conclusion

The prevalence of hypothyroidism among children and adolescent with nephrotic syndrome attending Mulago Hospital paediatric kidney clinic was 23%. Hypolbuminemia was found to be associated with hypothyroidism. Therefore, children and adolescents that have severely low levels of serum albumin should be screened for hypothyroidism and linked to endocrinologists for care.

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