[Blood erythropoietin levels in healthy subjects studied in the valley of Mexico]. / Niveles séricos de eritropoyetina en sujetos sanos estudiados en el valle de México.

Erythropoietin (EPO) is the hematopoietic growth factor that regulates red cell production. There is a direct relationship between its secretion and tissue hypoxia. Above sea level, oxygen concentration diminishes. This causes an increase of hemoglobin and hematocrit; this effect could be the consequence of higher EPO levels. Currently, evaluation of baseline serum EPO levels is very important in the differential diagnosis of anemia and erythrocytosis. The purpose of the present work was to report the EPO levels on a group of healthy blood donors living in Mexico City, 2,240 m above sea level. Two-hundred twenty blood donors were selected to measure serum EPO; there were 168 males and 52 females. Median EPO levels of the entire population were 7.5 mU/mL (percentile interval, PI, 1-18). Median EPO levels were 7.6 (PI 1-18) and 7.5 (PI 1-16.9) for men and women, respectively. We did not find differences in serum EPO levels among previous reports in other populations and the values determined in this study.

[Thyroid function tests in healthy and ill elderly]. / Pruebas de función tiroidea en ancianos sanos y enfermos.

Thyroid function in the elderly has been a matter of discussion. The universe of the present study includes males and females 36 hospitalized with an average age of 72.97 +/- 8.70 years (group I) and 36 ambulatory asymptomatic elderly with 69.81 +/- 8.55 years of age (group II). Serum levels of T3, T4, T4L and TSH were measured in both groups. Mean values of T3 were significantly lower in the hospitalized patients than in the control group. The difference persisted on both, males and females, analyzed separately. Mean values of T4L were significantly lower in women of group II, while mean values of T3 were significantly lower in men of group I. The comparison of thyroid function tests in male and female showed that serum values of T3 and T4 were significantly lower in men of group I. By dividing results in age categories, serum levels of T4L in group II were significantly lower in the age group of 70 to 79 and 80 to 89. Thyroid function tests in asymptomatic ambulatory elderly tend to be normal, whereas the hospitalized patients showed a high proportion of alterations.