Hypovitaminosis D and secondary hyperparathyroidism in resident physicians of a general hospital in southern Brazil

OBJECTIVES

To evaluate the prevalence of hypovitaminosis D and secondary hyperparathyroidism in resident physicians of a general hospital in southern Brazil and identify associated factors.

DESIGN

Cross-sectional study.

POPULATION

Resident physicians of Hospital de Clinicas de Porto Alegre, Porto Alegre, southern Brazil.

PARTICIPANTS

Seventythree subjects age 26.4+/-1.9.

MEASUREMENTS

Serum PTH, 25- hydroxyvitamin D [25(OH)D], total calcium, phosphorus, magnesium, creatinine, and alkaline phosphatase were measured. In addition calcium, creatinine, and magnesium were measured in urine. Fractional excretion of calcium and magnesium were calculated. Calcium intake was estimated by a food intake questionnaire.

RESULTS

Mean serum levels of 25(OH)D were 17.9+/-8.0 ng/ml and 57.4% presented 25(OH)D below 20 ng/ml. Secondary hyperparathyroidism, defined as serum PTH > or =48 pg/ml and normal or low serum calcium, was identified in 39.7% of the individuals. Mean serum levels of magnesium were higher (p=0.02) and the fractional excretion of calcium was lower (p<0.001) in individuals with secondary hyperparathyroidism. Serum PTH levels were positively correlated with body mass index (r=0.33 and p=0.006) and serum magnesium levels (r=0.33 and p=0.02) and negatively correlated with serum 25(OH)D levels (r=-0.33 and p=0.008), estimated calcium intake (r=-0.25 and p=0.04), and fractional excretion of calcium (r=-0.34 and p=0.009).

CONCLUSION

Vitamin D deficiency and secondary hyperparathyroidism was very common in resident physicians. Therefore, measures to prevent this situation should be recommended.

ATP diphosphohydrolase in human platelets from patients with coronary arteries heart disease

ATP diphosphohydrolase is an enzyme described in platelets and may be related to the control of ADP-dependent platelet aggregation. Platelet aggregation in atherosclerotic coronary arteries, and the release of platelet-derived factors, play an important role in coronary artery disease syndromes. In this study, we determined the activity of ATP diphosphohydrolase in platelets from patients with chronic and acute coronary artery disease syndromes and healthy persons. The following groups were studied: healthy persons (group I), patients with chronic heart disease (group II) and acute heart disease (group III). Results did not demonstrate differences between the groups studied. The control group demonstrated a lower range of enzyme activity. The patients from groups II and III had ingested drugs with actions upon the cardiovascular system and the effect, in vitro, of these drugs upon the ATP diphosphohydrolase activity in human platelets was also investigated. The in vitro experiments demonstrated that 2.0 mM acetylsalicylic acid inhibited ATP hydrolysis by human platelets by approximately 55%. Significant correlation was observed between ADP hydrolysis and glucose blood levels in the control group and between ATP hydrolysis and triglycerides in the group II. These results contribute to our understanding of a possible relationship between ATP diphosphohydrolase and thrombogenesis.

Pleural fluid adenosine deaminase and lymphocyte proportion: clinical usefulness in the diagnosis of tuberculosis

Adenosine deaminase (ADA) and lymphocyte proportion are known to be independently elevated in tuberculous effusions, but are non-specific, and false positive results are frequent. To overcome this problem the combined use of both parameters was prospectively studied in 276 patients with pleural effusion seen at Porto Alegre, Brazil. Using a cut-off level of 40 U/l at 37 degrees C (method of Giusti19) for ADA activity and lymphocyte proportion of more than 50%, the correct diagnosis of tuberculosis (sensitivity) was made in 90.7% (CI 87.3-94.1%) of 54 patients. A specificity of 97.7% (CI 95.9-99.5%) was recorded. Five false positive diagnoses of tuberculous effusion were made. Five false negative diagnoses were made: three cases with haematogenous tuberculous dissemination with low ADA levels, and two other patients with low lymphocyte proportion. The combined use of ADA activity determination and lymphocyte proportion is a highly efficient diagnostic strategy of low cost, that merits wider use.