Subclinical hypothyroidism and diabetic nephropathy. Could L-thyroxine replacement therapy be of value?

Dear Sir; We read with interest the study by Furukawa et al. The authors reported a significant and independent association of subclinical hypothyroidism (SCH) with nephropathy (defined as albumin:creatinine ratio >- 300 mg/g creatinine) in patients with diabetes mellitus (DM). In particular, those with diabetic nephropathy had more than two-fold higher prevalence of SCH than those without. Estimated glomerular filtration rate (eGFR) was lower in patients with SCH compared with euthyroid subjects. Some comments might be of interest. Although many studies have shown an association between overt -in most cases- hypothyroidism and renal dysfunction, what appears to be of outmost importance is whether restoration of thyroid function with L-thyroxine could be beneficial and to what extent, especially in patients with DM. It is well-known that SCH affects many cardiovascular parameters involved in the pathogenesis of diabetic nephropathy, such as lipids and blood pressure.