A Case of Acquired LCAT Deficiency with the Discrepancy between Spontaneous Resolution of Proteinuria and Continually Low HDL Cholesterol Levels

A 79-year-old Chinese man was referred for nephrotic syndrome (proteinuria 4.4 g/day). In blood tests, serum high-density lipoprotein (HDL) cholesterol was undetectable, and the esterified cholesterol to total cholesterol ratio was very low. Lecithin: cholesterol acyltransferase (LCAT) activity was also undetectable. Since he had neither corneal opacity nor pathological mutations in the LCAT gene and anti-LCAT antibodies were detected in serum, a diagnosis of acquired LCAT deficiency was made. Renal biopsy revealed glomerulopathy associated with LCAT deficiency and membranous nephropathy (MN). Since the patient’s proteinuria did not improve despite prescribing an angiotensin II receptor blocker (ARB), we suggested the prescription of prednisolone, but he returned to China due to the expiration of his residence visa for Japan. One year after the initial visit, his proteinuria had improved to 0.9 g/day without immunosuppressive therapy. However, his HDL cholesterol level was still low at around 3 mg/dL, indicating a discrepancy between remission of nephrotic syndrome and lack of improvement in lipid levels.
Of the 11 patients with acquired LCAT deficiency reported to date, 4 with undetectable LCAT activity and MN on renal biopsy required immunosuppressive therapy to alleviate proteinuria. The present patient was prescribed only an ARB according to his preference, which happened to be consistent with the MN treatment guideline that states, “Wait 6 months for spontaneous remission while using maximal antiproteinuric therapy.” The clinical course of acquired LCAT deficiency varies, and further case reports are needed to determine the necessity of immunosuppressive therapy.