Vitamin D deficiency in community-acquired pneumonia: low levels of 1,25(OH)2 D are associated with disease severity.

OBJECTIVES: We aimed to explore the association between vitamin D levels and the severity, mortality and microbiological etiology of community-acquired pneumonia. METHODS: Vitamin D levels (both, the reservoir form 25-OH and the activated form 1,25-OH2) of 300 randomly selected patients with community-acquired pneumonia due to pre-specified pathogens included in the German competence network (CAPNETZ) study were measured. Prior to statistical analysis, values of 25-OH and 1,25-OH2 were power-transformed to achieve parametric distribution. All further analyses were performed with seasonally and age adjusted values. RESULTS: There was only a modest (Spearman Coefficient 0.38) positive correlation between 25-OH and 1,25-OH2. For 1,25-OH2 but not 25-OH, the general linear model revealed a significant inverse correlation between serum concentration and CURB score (p = 0.011). Liver and respiratory co-morbidity were associated with significantly lower 25-OH values and renal co-morbidity with significantly lower 1,25-OH2 values. No significant differences of 1,25-OH2 or 25-OH between different pathogens (influenza virus, Legionella spp., Streptococcus pneumoniae) were detected. CONCLUSION: For 1,25-OH2, we found a significant and independent (controlled for age, season and pathogen) negative correlation to pneumonia severity. Therefore, supplementation of non-activated vitamin D to protect from pneumonia may be non-sufficient in patients that have a decreased capacity to hydroxylate 25-OH to 1,25-OH2.

Sympathoadrenal counterregulation in patients with hypothalamic craniopharyngioma.

In humans, the role of hypothalamic centers for activation of counterregulatory release of catecholamines and glucagon during hypoglycemia is unclear. To address this question, we investigated the counterregulatory response to acute insulin-induced hypoglycemia of glucagon, epinephrine, and norepinephrine in eight patients who had undergone transcranial surgery for a craniopharyngioma extending to the hypothalamic region. We compared the patients' responses with those of four patients suffering from hypopituitarism and of six healthy subjects. After the i.v. injection of 0.1 U of human insulin per kg of body weight in the patients or 0.15 U in healthy subjects, the plasma glucose concentrations decreased to similar minimum levels within 30 min in all three groups. All subjects recovered spontaneously from hypoglycemia within 2 h. In five of eight craniopharyngioma patients, only a small counterregulatory rise in plasma epinephrine (< or =2-fold) and norepinephrine could be observed (P < 0.05 for epinephrine and P = 0.22 for norepinephrine vs. healthy controls). During hypoglycemia, virtually no adrenergic symptoms (tremor, heart pounding, and anxiety) were reported by these five patients, and changes in the heart rate were diminished. In three craniopharyngioma patients, the counterregulatory increase in catecholamines was unimpaired, adrenergic symptoms were reported and a rise in heart rate was observed during hypoglycemia. In all craniopharyngioma patients, the counterregulatory glucagon response to hypoglycemia was preserved and orthostasis increased both catecholamines and the heart rate similar to in the patients with hypopituitarism as well as in the healthy controls. Our results demonstrate selective impairment of counterregulatory sympathoadrenal activation in patients who had undergone surgery for a craniopharyngioma extending to the hypothalamic region. This strongly suggests the involvement of hypothalamic centers in hypoglycemia-induced activation of the sympathoadrenal axis in humans. It remains unclear as to whether hypoglycemia-induced glucagon secretion is also controlled by the hypothalamus. However, a common hypothalamic center controlling both counterregulatory catecholamine and glucagon release is unlikely, and sympathoadrenal activation is not required for hypoglycemia-induced glucagon secretion in humans.