Hyperthyroidism influences renal function

Area of Science:

• Nephrology
• Endocrinology
• Internal Medicine

Background:

• Hypothyroidism's renal effects are well-documented, but hyperthyroidism's impact on kidney function is less understood.
• This study investigates the renal effects of hyperthyroidism, specifically focusing on estimated glomerular filtration rate (eGFR).

Purpose of the Study:

• To determine the effect of overt and subclinical hyperthyroidism on eGFR.
• To assess changes in eGFR after achieving euthyroidism in a large cohort of hyperthyroid patients.

Main Methods:

• Included 433 patients with overt or subclinical hyperthyroidism.
• Measured serum fT3, fT4, TSH, BUN, creatinine, and eGFR in both hyperthyroid and euthyroid states.
• Calculated eGFR using the simplified Modification of Diet in Renal Disease (MDRD) formula.

Main Results:

• Achieving euthyroidism significantly decreased fT3, fT4, and eGFR, while increasing BUN, creatinine, and TSH.
• Significant correlations were found between eGFR and fT3/fT4 levels during the hyperthyroid state.
• No significant difference in eGFR change was observed between overt and subclinical hyperthyroid groups.

Conclusions:

• A notable decline in eGFR was observed post-treatment, indicating hyperthyroidism may mask mild renal insufficiency.
• Some patients exhibited eGFR below 60 mL/min/1.73 m², suggesting potential underlying kidney issues.