Velibor Čabarkapa, Zoran Stošić, Radmila Žeravica, Branislava Ilinčić and Ana Filipović
The Importance of Holotranscobalamin Measurement
Clinically significant vitamin B12 deficiency can occur even with total vitamin B12 levels apparently within normal range. There is an indeterminate zone between approximately 154 and 300 pmol/L of vitamin B12 where there is likely misclassification of B12 status if relying on total serum B12. The aim of the present study was to assess the usefulness of holotranscobalamin in diagnosis of B12 deficiency. Blood samples were collected and subjected to assays for vitamin B12 and holotranscobalamin. We examined the levels of holotranscobalamin in 32 subjects (n=32, f=18, m=14) with vitamin B12 values within interval 154-300 pmol/L. These subjects were compared with control group with vitamin B12>300 pmol/L (n=31, f=17, m=14). 25% of subjects with vitamin B12 of 154 to 300 pmol/L had low levels of holotranscobalamin. Holotranscobalamin levels of patients with vitamin B12 of 154 to 300 pmol/L were significantly lower than those of control subjects (38.55 ± 23.0 vs. 61.35 ± 31.81 pmol/L, p<0.01). The obtained results also show a positive significant relationship between levels of holotranscobalamin and vitamin B12 (r=0.53, p<0.01). In conclusion, holotranscobalamin is a better indicator of early vitamin B12 deficiency than total serum cobalamins and it is a useful tool in the diagnosis of vitamin B12 deficiency.
Velibor Čabarkapa, Zoran Stošić, Radmila Žeravica and Branislava Ilinčić
Hyperhomocysteinemia in Chronic Renal Insufficiency
Hyperhomocysteinemia is an independent risk factor for premature cardiovascular disease. Since the homocysteine level is elevated in patients with advanced chronic renal insufficiency, it has been presented as an important factor contributing to the development of cardiovascular complications in these patients. In this study we examined the level of homocysteine in patients with mild-moderate degree of glomerular filtration rate reduction (creatinine clearance >40 mL/min and <80 mL/min/1.73 m2). Thirty patients (f=15, m=15) were compared with healthy subjects (n=32, f=17, m=15). Blood samples were collected and subjected to assays for homocysteine, creatinine, creatinine clearance. The results show that homocysteine levels of patients were significantly higher than those of healthy subjects (12.75 ± 3.9 vs. 8.5 ± 1.75 μmol/L, p<0.001). The obtained results also show a significant negative relationship between the level of homocysteine and creatinine clearance (r=-0.8). In conclusion, hyperhomocysteinemia is a common finding not only in advanced chronic renal insufficiency, but also in patients with mild-moderate reduction of glomerular filtration rate, and may significantly contribute to premature development of cardiovascular complications.
Velibor Čabarkapa, Romana Mijović, Zoran Stošić, Nikola Ćurić, Radmila Žeravica and Branislava Ilinčić
Estimation of Glomerular Filtration Rate From Serum Cystatin C and Creatinine in Patients with Thyroid Dysfunction
Given that thyroid function influences serum cystatin C and creatinine levels, the question arises as to whether it is possible to accurately estimate glomerular filtration rate (GFR) in patients with thyroid dysfunction. The objective of the study was to determine serum cystatin C and creatinine levels and estimate GFR in patients with thyroid dysfunction. The study included 32 cases with newly diagnosed hyperthyroidism and 27 cases with newly diagnosed hypothyroidism, as well as 20 healthy controls matched for sex and age with the cases. Serum concentrations of thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4), creatinine and cystatin C were measured in all study subjects. GFR was estimated using the Modification of Diet in Renal Disease (MDRD), the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and cystatin C-based equations. Serum cystatin C levels were significantly higher in hyperthyroid subjects compared to controls (1.32±0.31 vs. 0.89±0.15; p<0.01). Serum creatinine levels were significantly lower in hyperthyroid subjects compared to controls (60.6±10.2 vs. 76.4±8.6; p<0.01), and significantly higher in hypothyroid subjects compared to controls (94.5±13.2 vs. 76.4±8.6; p<0.01). GFR estimated with the MDRD equations was significantly higher in hyperthyroid subjects compared to hypothyroid subjects (101.6±20.7 vs. 64.1±11.6 mL/min/1.73m2; p<0.01). GFR estimated with the equation based on serum cystatin C was significantly lower in hyperthyroid subjects compared to hypothyroid subjects (59.2±22.1 vs. 92.1±16.0 mL/min/1.73m2; p<0.01). Although serum cystatin C is regarded a reliable marker of GFR and more sensitive than serum creatinine, it has limitations in patients with thyroid dysfunction, due to significant changes in its serum concentrations regardless of renal function. In patients with thyroid dysfunction GFR should therefore be estimated using the equations based on serum creatinine.
Serum Cystatin C in Estimating Glomerular Filtration Rate
Using serum cystatin C in estimating glomerular filtration rate (GFR) has in recent times been recommended. A number of simple formulas for calculating GFR have been derived specifically from serum cystatin C concentrations. The purpose of this study was to assess the significance of cystatin C and of the two most frequently applied of these formulas in estimating glomerular filtration rate compared to serum creatinine and its derived formulas for estimating glomerular filtration rate from creatinine concentrations. The study included 74 patients: 59 were in various stages of chronic renal insufficiency (divided into two subgroups: I with GFR ≥ 60 mL/min/1.73m2 and II with GFR<60 mL/min/1.73m2) and 15 on hemodialysis. A control group of 30 healthy participants was also included in the study. Serum values of cystatin C ranged from: 0.86 ± 0.16 mg/L in subgroup I, and 1.77 ± 0.79 mg/L in subgroup II, to 6.9 ± 1.83 mg/L in patients on hemodialysis. The correlation between the two formulas derived from cystatin C and the clearance of creatinine, as well as the Cockcroft and Gault's formula, was significant, while one of the formulas derived from cystatin C did not show a significant correlation with MDRD. It was concluded that serum cystatin C is a significant marker in estimating glomerular filtration rate, especially in the advanced stages of chronic renal insufficiency.
Velibor Čabarkapa, Branislava Ilinčić, Mirjana Đerić, Isidora Radosavkić, Mirko Špovac, Jan Sudji and Veljko Petrović
Background: Chronic kidney disease (CKD) is one of the most significant global health problems accompanied by numerous complicatons, with constant increase in the number of affected people. This number is much higher in early phases of disease and patients are mostly asymptomatic, so early detection of CKD is crucial. The aim was examination of the prevalence of CKD in the general population of males in Vojvodina, based on estimated glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (ACR), and exploring the determinants and awareness of CKD.
Methods: This cross-sectional study included 3060 male examinees from the general population, over 18 years of age, whose eGFR and ACR were calculated, first morning urine specimen examined, arterial blood pressure measured and body mass index calculated. Standard biochemistry methods determined creatinine, urea, uric acid and glucose serum concentrations as well as albumin and creatinine urine levels.
Results: Prevalence of CKD in the adult male population is 7.9%, highest in men over 65 years of age (46.7%), while in the other age groups it is 3.6-12.6%. The largest number of examinees with a positive CKD marker suffer from arterial hypertension (HTA) and diabetes mellitus (DM). Only 1.3% of examinees with eGFR<60 ml/min/1.73 m2 and/or ACR≥ 3 mg/mmol had been aware of positive CKD biomarkers.
Conclusions: Obtained results show the prevalence of CKD in adult males is 7.9%, HTA and DM are the most important CKD risk factors and the level of CKD awareness is extremely low (1.3%) indicating the necessity for introduction of early stage disease recognition measures, including raising CKD awareness.