Urinary Albumin Excretion in Patients with Familial Mediterranean Fever: A Pilot Study

Amyloidosis of the kidney is the most threatening complication in familial Mediterranean fever (FMF), and colchicine has been shown to reduce its occurrence. In the preclinical stage of kidney amyloidosis, no proteinuria is observed by the standard Albustix method. However, whether these patients have normal or increased urinary albumin excretion is not known. The purpose of this study was to evaluate albumin excretion in FMF patients treated with colchicine and to compare these values to those of a normal control group. Twenty-two subjects with FMF were compared with 16 normal subjects matched with regard to age and body surface area. The two groups did not differ with regard to female/male ratio and arterial pressure. Urine samples were collected overnight while patients were recumbent and in the daytime while they were ambulant. After measuring albumin concentration (Ua) by radio-immunoassay and creatinine concentration through the standard method, the urinary albumin excretion rate (UaV) and urinary albumin creatinine ratio (Ua/ c) were calculated. In the FMF group, three patients had microalbuminuria —defined as an albumin excretion rate higher than 20 μg/min. Two of them had this condition only in the early morning collection. These three patients were characterized by a longer duration of symptoms (18 vs. 9 years). No patient in the control group had microalbuminuria. The mean UaV in the FMF group did not differ significantly from that of the control group. However, in the control group the albumin excretion in the early morning sample was only slightly greater than that in the night samples, but in the FMF group the three indices of albumin excretion — Ua, UaV and Ua/ c — were significantly greater (p < 0.01) in the morning than at night. This exaggerated pattern of response to orthostatic changes in albumin excretion might indicate a subtle glomerular damage in these patients.