Low T3 Syndrome in Adult Patients with Nephrotic Syndrome

OBJECTIVE: The aim of this study is to evaluate the frequency of thyroid dysfunction in adult patients with nephrotic syndrome and to investigate the relation between nephrotic syndrome and low triiodothyronine (T3) syndrome. MATERIAL and METHODS: Thirty three adult patients with nephrotic syndrome and 20 healthy controls were included in the study. Serum thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were measured by chemiluminescent immunoassay. Proteinuria was measured in a 24-hour urine collection. Estimated Glomerular Filtration Rate (eGFR) was calculated by the Modification of Diet in Renal Disease (MDRD) equation. RESULTS: The mean age of the patients was 49 +/- 17 years. The mean levels for the parameters measured were as follows: serum albumin, 22 +/- 5 (g/L); urinary protein excretion in 24 hour collections, 7.8 +/- 4.5 (g/day), serum creatinine 1.32 +/- 0.66 (mg/dL); serum TSH, 3.2 +/- 3.1 (mIU/mL).; fT3, 2.5 +/- 0.6 (pg/mL), and fT4, 1.0 +/- 0.30 (ng/dL). In nephrotic syndrome patients, the mean serum TSH level was significantly higher whereas mean fT3 level was significantly lower when compared to the levels in the control group. Serum fT3 level correlated positively with serum albumin (r: 0.56, p:0.01) and fT4 (r: 0.51, p: 0.03) and negatively with total cholesterol (r:-0.39, p: 0.03). Seven (21%) patients were hypothyroid, 3 (9%) were hyperthyroid, and 11 (33%) had low T3 syndrome. CONCLUSION: Thyroid dysfunction, low T3 syndrome in particular, is frequent in adult patients with nephrotic syndrome. The free T3 level correlates with the severity of nephrotic syndrome. Further studies are necessary regarding the clinical importance of low T3 syndrome.