Although lecithin-cholesterol acyltransferase (LCAT) deficiency has been previously described in patients of European descent, recent evaluations of patients suggest that this disorder should not be ruled out as a possible cause of nephrotic syndrome in patients of other races as well.
Two cases of African American women with LCAT deficiency were presented by Melissa Makar, MD, and Eugene C. Kovalik, MD, of Duke, at the American Society of Nephrology's annual meeting held October 31 to November 5, 2017, in New Orleans, LA.
In the first case, a 30-year-old African American woman was evaluated for proteinuria and hematuria that was discovered on a routine urinalysis conducted as part of a preoperative evaluation for hysterectomy. This patient had lower-extremity edema, an estimated glomerular filtration rate (eGFR) of 115 mL/min/1.73 m2, and 9.1 g of proteinuria on 24-hour urine collection. Serologies were negative, and, on kidney biopsy, light microscopy showed vacuolization of her capillary loop basement membranes. Electron microscopy showed subendothelial intermembranous and mesangial deposits of lamellated, myelin-figure lipid material, along with mesangial and endocapillary foam cells.
Consistent with LCAT deficiency, HDL and cholesteryl ester levels were low: 8 mg/dL and 13%, respectively. Despite blood-pressure control with an angiotensin-converting enzyme inhibitor (ACEI), the patient progressed to end-stage kidney disease at age 36. Two years later, she underwent a deceased donor kidney transplant and, although the condition can recur after transplant, she has been doing well since that procedure.
In the second case, a 69-year-old African American woman with a longstanding history of dyslipidemia was referred to Duke for an HDL of less than 5 mg/dL. A low cholesteryl ester level of 15% confirmed the diagnosis of LCAT deficiency. At that time, the patient's eGFR was 102 mL/min/1.73 m2, and she had no proteinuria while taking 3 antihypertensive agents, including an ACEI. Over the following 7 years, however, her eGFR fell to 52 mL/min/1.73 m2, and she developed proteinuria (4 g on spot check). A subsequent full evaluation was otherwise negative, and she is being followed closely as an outpatient.
Since LCAT was discovered in 1967, only about 70 cases have made it into the literature, and most of the patients in these cases were of European decent, with a few being Japanese. "What we have learned from these 2 cases is that any time you see a patient with nephrotic syndrome, check the lipid panel,” Makar advised. ”And if the HDL is low, then LCAT should definitely be on the differential.” The diagnosis can be confirmed with low serum cholesteryl ester levels, along with diffuse foam cells and lipid deposits observed on kidney biopsy. Makar and Kovalik noted that individuals with LCAT deficiency should receive supportive care with renin-angiotensin-aldosterone system blockade and diuretics.
Source: Makar M, Kovalik EC. An unusual cause of nephritic syndrome: LCAT deficiency. Presented at: American Society of Nephrology annual meeting, Kidney Week 2017; October 31-November 5, 2017; New Orleans, LA. Poster 621.