Impact of experimental hypercalcemia on routine haemostasis testing.

BACKGROUND: The blood to anticoagulant ratio is standardized according to the physiological calcium concentration in blood samples conventionally used for hemostasis testing. Specifically, one fixed volume of 0.109 mmol/L sodium citrate is added to 9 volumes of blood. Since little is known about the impact of hypercalcemia on the calcium-binding capacity of citrate, this study was planned to investigate the effect of experimental hypercalcemia on routine hemostasis testing. METHODS: Fifteen pooled citrated plasmas with matching lithium-heparin pooled plasma from patients with different values of prothrombin time (PT) were divided in three aliquots of 0.6mL each. The first paired aliquots of both citrate and lithium-heparin plasma were supplemented with 60µL of saline, the second paired aliquots with 30µL of saline and 30µL of calcium chloride and the third paired aliquots with 60µL of calcium chloride. Total and ionized calcium was measured in all aliquots of citrate and lithium-heparin plasma, whereas PT, activated partial thromboplastin time (APTT) and fibrinogen were measured in citrate plasma aliquots. RESULTS: Total calcium concentration gradually increased in both lithium-heparin and citrate plasma aliquots 2 and 3 compared to baseline aliquot 1. The concentration of ionized calcium also gradually increased in lithium-heparin plasma aliquots 2 and 3, whereas it remained immeasurable (i.e., <0.10 mmol/L) in all citrate plasma aliquots. No significant differences were observed for values of PT, APTT and fibrinogen in citrate plasma aliquots 2 and 3 compared to the baseline aliquot 1, with a mean bias was always comprised within the desirable quality specifications derived from biological variability data. CONCLUSION: Hypercalcemia, up to severe hypercalcemia does not generate significant bias in results of first-line coagulations tests, so that hypothetical consideration of adjusting citrate-blood ratio is unjustified in hypercalcemic patients.

The burden of vitamin D deficiency in a mediterranean country without a policy of food fortification.

BACKGROUND: Vitamin D deficiency is a public healthcare issue and its correction is increasingly regarded as a cornerstone of preventive medicine. METHODS: We designed a retrospective observational study to clearly define the burden of total vitamin D (25-hydroxyvitamin D) deficiency in a supposedly healthy population of outpatients residing in two regions (Emilia Romagna and Veneto) of Northern Italy. RESULTS: 25-hydroxyvitamin D results were available for a total number of 5,096 outpatients in the two centers. The median value of 25-hydroxyvitamin D was 60 nmol/L, and was higher in women than in men (62 nmol/L versus 56 nmol/L; p<0.001). The rate of 25-hydroxyvitamin D deficiency was 36%, and was marginally but significantly higher in men than in women (40% versus 35%; p=0.003). A significant variation in the rate of 25-hydroxyvitamin D deficiency was found throughout different age ranges, exhibiting a significant increase in the elderly. CONCLUSIONS: The results of this large observational study show that the burden of 25-hydroxyvitamin D deficiency in two regions of a Mediterranean country without a policy of food fortification is as high as 36%, and this evidence represents a background for healthcare preventive measures aimed at reducing the prevalence of this condition in the general population. (www.actabiomedica.it).

Inhibition of xanthine oxidase and exercise on serum uric acid, 25(OH)D3, and calcium concentrations.

BACKGROUND: It has been shown that serum concentrations of 1,25(OH)2D3 are decreased in patients with gout. A short-term administration of allopurinol increases plasma concentrations of 1,25(OH)2D3 in mild to moderate renal failure, with or without hyperuricemia. It has been reported that subjects who perform regular vigorous and/ or moderate physical activities have higher plasma and serum 25(OH)D3 levels. However, little is known about the influence of allopurinol and/or physical exercise on serum 25(OH)D3 concentrations in humans. METHODS: We investigated the effect of allopurinol administration and/or physical activity on vitamin D metabolism by measuring serum uric acid, 25(OH)D3, and calcium levels in twelve professional soccer players. RESULTS: The athletes supplemented with allopurinol, but not those who received placebo, exhibited a significant decrease in uric acid serum concentrations after the match. We also found a significant increase in serum calcium and 25(OH)D3 concentrations in the supplemented group. CONCLUSIONS: We conclude that allopurinol administration might be an effective drug to lower hyperuricemia and treat hypovitaminosis D.

Serum ferritin as a marker of potential biochemical iron overload in athletes.

OBJECTIVES: Beyond hematological manipulation, iron supplementation therapy is commonplace in athletes to counterbalance physiological or pathologic anemia and to prevent physiologic dysfunction. However, misuse of iron therapy, occasionally resulting in iron overload, is not free from metabolic risks. DESIGN: We planned to measure baseline serum ferritin concentration in sedentary individual and athletes. SETTING: The Institute of Clinical Biochemistry of the Verona University. PARTICIPANTS Serum ferritin was measured in 60 male healthy sedentary controls, 80 amateur road cyclists, 42 male professional cross-country skiers, and 88 professional male road cyclists. ASSESSMENT OF RISK FACTORS: The biochemical iron overload was ascertained by measuring baseline serum ferritin concentration as a reliable approach that mirrors the total body iron content. MAIN OUTCOME MEASUREMENTS: The concentration of serum ferritin in healthy controls was 112 +/- 78 ng/mL, whereas that of amateur cyclists, professional skiers, and professional cyclists was 127 +/- 76 ng/mL (P = 0.185), 183 +/- 130 ng/mL (P = 0.001), and 332 +/- 218 ng/mL (P < 0.001), respectively. RESULTS: Both categories of professional athletes showed significantly increased concentrations of serum ferritin, whereas the concentration of amateur cyclists was comparable to that of healthy sedentary controls. CONCLUSIONS: Professional endurance athletes have serum ferritin concentrations that are 2-fold to 3-fold higher than those of matched sedentary individuals and amateur athletes, exceeding the threshold for the diagnosis of biochemical iron overload and unveiling potential metabolic risks.