ESPE Abstracts

Introduction: Thyroid hormone (TH) is important for normal growth and function of kidneys [1,2]. Hypothyroidism decreases responsiveness to B-adrenergic stimulation resulting in diminished cardiac contractility, blood pressure, and vasodilator secretion leading to lower renal blood flow [3]. Glomerular filtration rate (GFR) can be reduced by up to 40% and a direct relationship between serum creatinine (SCr) and thyroid-stimulating hormone (TSH) levels was elicited [3]. Moreover, kidneys size and structural changes were detected in experimental animals with hypothyroidism [4]. We present a hypothyroid child with the diagnosis of stage-2 chronic kidney disease (CKD) whose SCr normalized with levothyroxine replacement.

Case Presentation: A 10-years-old boy has been following-up for 25 months for an unexplained raised SCr. He presented several times with fever, coryzal and gastrointestinal symptoms when investigations showed a persistently elevated SCr even after adequate hydration, with otherwise normal kidney function and electrolytes. There was no family history of CKD and his blood pressure was normal throughout his illness. On initial assessment, estimated GFR using the bedside Schwartz formula was 58 ml/min/1.73m2, indicating stage-3 CKD according to the KDIGO guidelines. Urinalysis revealed no blood or casts. Moreover, urine for protein/calcium to creatinine ratio, parathyroid hormone, complement C3/C4, antinuclear antibody and creatinine kinase were all normal. Kidneys were slightly small in size on ultrasonographic scan, however its shape and corticomedullary differentiation were preserved with no evidence of nephrocalcinosis. In subsequent follow-up visits, estimated GFR improved to 62ml/min/1.73m2. He was labelled as CKD stage-2 patient and planned for a renal biopsy. Thyroid function test (TFT) was never done throughout this period; however, it was eventually requested when family reported fatiguability and weight gain (8 kg in 10 months). On assessment, the patient had growth deceleration (growth velocity dropped to 1.3 cm/year) but no goiter or other signs of hypothyroidism. TSH was significantly high [> 100 mIU/L] and free thyroxine was low [3.2 pmol/L (8.1-14.9)]. While Thyroid Peroxidase Antibody was slightly elevated [22 kIU/L (0-10)], anti-thyroglobulin antibody was normal. Five days following levothyroxine initiation, SCr dramatically normalized (estimated GFR 93 ml/min/1.73m2) and the patient became clinically and biochemically euthyroid in 3 months with 75 mg of daily levothyroxine.

Conclusion: TH is important for normal growth, metabolism and body organ’s function. TFT is a routine test in many different disorders and hypothyroidism has to be considered in every patient with unexplained elevated SCr or renal impairment.