P254Cystatin C: Marker of cardiac damage in patients with arterial hypertension

Abstract

Purpose: Levels of urinary albumin excretion that are below the usual limit of detection by qualitative testing, but are above normal levels (microalbuminuria; MA), can be readily identified by simple measures, such as the urinary albumin to creatinine ratio in untimed urine samples. In hypertensive patients presence of microalbuminuria (MA) is related to renal and cerebral damage and is considered an early sign of cardiac damage. Cystatin C, a member of the cysteine proteinase inhibitor family, is a small 13 – kDa protein: it is produced at a constant rate by nucleated cells. Due to its small size the protein is freely filtered by the glomerulus, and is not secreted but is fully reabsorbed and broken down by the renal tubules. This means that the main determinant of blood Cystatin C levels is the rate at which it is filtered at the glomerulus making it an excellent and sensible plasmatic marker of glomerular speed filtration. Therefore Cystatin C can be considered an early marker of cardiac damage in arterial hypertension (AH) instead of MA. We evaluated the behaviour of Cystatin C in hypertensive patients to verify its usefulness as a marker of cardiac damage. Methods: We examinated for six months 360 pts (198 males and 162 females), aged between 46 and 64 years, no smokers, with two-year history of AH, without diabetes or cardiovascular diseases and with normal lipids. They underwent to laboratory tests (as the G.L. ESC/ESH 07), CC (done with nephelometric method BNAII: normal value 0,53/0,95 mgr/l), and instrumental exams: supra-aortic truncus and renal arteries Echo-Doppler, ECG, Echocardiogram. Results: All patients have normal values of MA, glycemia and creatinin clearance. Hundred eighty-eight patients (86 M, 102 F) have a medium increase of CC over 1,1±0,2. A left ventricular hypertrophy was present in 30 patients (18M , 12F) with left ventricular mass >110gr/m2 (F) and 125 g/m2 Ninety-eight (76M, 22 F) presented an increase of medio-intimal tickening >0,9 mm (mean 1,2) and LVH. In 60 patients (38M, 22 F) no organ damage was documented. In all patients, Doppler examination of the renal arteries was normal. Conclusions: Cystatin C can be considered an early economic and sensible marker of cardiac damage in hypertensive patients. It is not influenced by age, sex, weight, muscular masses. Its increase should push to investigate and evaluate the state of the heart, brain and kidneys.