Fibroblast Growth Factor-23 and Carotid Artery Intima Media Thickness in Chronic Kidney Disease.

BACKGROUND: The cause of early-accelerated atherosclerosis development observed in Chronic Kidney Disease (CKD) is not fully understood. The determination of the relationship between the levels of fibroblast growth factor 23 (FGF-23) and the development of endothelial dysfunction, left ventricular hypertrophy, and myocardial infarction lends support to the possibility that FGF-23 plays a role in the development of atherosclerosis in CKD. Only a few studies, however, have been conducted that analyze the relationship between FGF-23 levels in the progression of CKD and the development of atherosclerosis, and these studies have generally been limited to those patients receiving dialysis therapy due to end stage renal disease (ESRD). METHODS: In the present study, carotid artery intima-media thicknesses (IMT) were measured ultrasonically as a marker of atherosclerosis in 91 patients with CKD stage 3 - 4 (61 female and 30 male, age between 19 - 65 years, glomerular filtration rate [GFR] 15 - 60 mL/min 1.73 m2, CKD was not related to diabetes mellitus, and without cardiovascular-cerebral disease) in contrast to 36 healthy volunteers (26 female and 10 male, age between 19 - 65 years, GFR > 90 mL/min 1.73 m2, and without any diagnoses of acute or chronic disease), and a possible role of FGF-23 on atherosclerosis was analyzed. RESULTS: Patients were similar to controls with respect to age, gender, smoking status, body mass index, and plasma glucose and lipid profile. On the other hand, IMT measurements (p < 0.00001) and FGF-23 levels (p = 0.00012) were significantly higher in patients than controls. IMT was measured above the subclinical atherosclerosis limit of 0.750 mm in 54% of the patients. Multivariate regression analysis showed that patients' age, high sensitive c-reactive protein (hsCRP), and FGF-23 levels were independent predictors of IMT (p < 0.00001, r = 0.559). Independent of other variables, every 1 µmol/L increase in FGF-23 levels resulted in 0.444 mm increase of IMT measurements in patients with CKD. CONCLUSIONS: Our findings suggest that monitoring serum FGF-23 may be useful as a non-invasive indicator of subclinical atherosclerosis in patients with chronic kidney disease.

Carotid intima media thickness is independently associated with urinary sodium excretion in patients with chronic kidney disease.

Atherosclerosis-induced premature vascular diseases are the leading cause of mortality among patients with chronic kidney disease (CKD). The pathogenetic mechanism of atherosclerosis in patients with CKD has not been fully explained. Experimental studies have demonstrated that high dietary sodium intake not only increases circulatory volume and blood pressure, but also facilitates development of atherosclerosis by reducing production-bioavailability of nitric oxide due to oxidative stress and accordingly by enhancing endothelial and arterial stiffness. In this study, we investigated the relationship between sodium consumption and carotid artery intima-media thickness, which is the indicator of atherosclerosis, by determining daily urinary sodium excretion, which is a reliable indicator of sodium consumption, in our patient group. Our patient group included 193 patients with stage 2-4 non-diabetic CKD and without a history of atherosclerotic disease. We determined that 77% of our patients have been consuming more than 2 g of sodium per day, which is the upper limit of sodium consumption recommended for patients with CKD. We determined a positive linear correlation between carotid artery intima-media thickness and patient age (p < 0.001), C-reactive protein (p < 0.001), urinary sodium excretion (p < 0.001), body mass index (p = 0.002), systolic blood pressure (p = 0.002), hemoglobin (p = 0.030), triglycerides (p = 0.043), and diastolic blood pressure (p = 0.049). We also found a negative linear correlation between carotid artery intima-media thickness and glomerular filtration rate (p = 0.008). We found that urinary sodium excretion is the determinant of intima-media thickness even if all factors associated with intima-media thickness are adjusted, and that intima-media thickness increases by 0.031 (0.004-0.059) mm per 2 g increase in daily sodium excretion, independent from overall factors (p = 0.025). Our results reveal a relation between urinary sodium excretion and carotid artery intima-media thickness and suggest that excessive sodium consumption predisposes development of atherosclerosis in patients with CKD.

The effects of spironolactone on nephron function in patients with diabetic nephropathy.

Increasing evidence suggests that circulating aldosterone per se contributes directly to renal and cardiovascular diseases. We sought to evaluate the effects of a three-month treatment with 25 mg spironolactone, an aldosterone receptor antagonist, on nephron function in 20 type II diabetic patients with persistent microalbuminuria, despite at least six months' use of an ACEi or ARB (combination group), and in eleven type II diabetic patients with persistent microalbuminuria who have never used an ACEi or an ARB (spironolactone group). In the combination group, urinary protein excretion (UPE, p = 0.015), urinary albumin excretion (UAE, p = 0.010), and the urinary albumin to creatinine ratio (ACR, p = 0.007) decreased, and serum potassium (sK(+), p = 0.004) was significantly elevated. ACR (p = 0.016) decreased significantly in the spironolactone group. In 31 patients given spironolactone (all patients group), UPE (p = 0.019), UAE (p = 0.002), and ACR (p = 0.011) decreased, and serum creatinine (sCr, p = 0.025) and sK(+) (p = 0.002) were significantly elevated. Changes in albuminuria showed a positive correlation with changes in GFR (p = 0.002) and a negative correlation with changes in sCr (p = 0.007), and changes in ACR showed a negative correlation with changes in sCr (p = 0.004) in all patient groups. In our study, we observed that spironolactone, both alone and in combination with ACEi/ARB treatment, was well tolerated, and that it slowed down the progression of diabetic nephropathy with a marked antialbuminuric effect. Our results showed that the antialbuminuric effect developed by the decrease of intraglomerular pressure, particularly in patients with persistent microalbuminuria despite long-term ACEi/ARB treatment; adding aldosterone blockers to treatment was beneficial.