Hyponatremia, Hypokalemia, and Fragility Fractures in Old Patients: More than an Association?

PURPOSE: Hyponatremia and hypokalemia are common among elderly and have been associated with osteoporosis, we evaluate the role of these electrolytes as risk for fragility fractures. METHODS: This study is divided in two parts: one retrospective and one prospective. We retrospectively collected data on urgently admitted patients for femoral fragility fractures (Fx) or for acute myocardial infarction (AMI), and patients admitted for elective hip/knee replacement surgery for osteoarthrosis (OA). Age, sex, serum sodium, potassium, creatinine, and comorbidities were recorded. We enrolled prospectively in-patients from our unit: age, sex, comorbidities, drugs, and fragility fractures were recorded. Blood electrolytes were measured. Cognitive function, nutrition, muscular strength, and balance were evaluated by standard tests. The mortality rate was recorded with a follow-up after hospital discharge. RESULTS: The retrospective study included 2166 subjects: 702 Fx and 1464 controls (907 AMI, 557 OA): the prevalence of hyponatremia was similar in Fx and AMI, whereas it was higher in Fx with respect to OA (p < 0.001) as well as hypokalemia (p < 0.001). Sodium decrease was associated with higher fracture risk. Among the 284 subjects included in the prospective study, 50 patients were hyponatremic, more likely malnourished, and presented a higher prevalence of fragility fractures (p = 0.008). They had a higher mortality after hospital discharge (HR = 1.80, p = 0.005), however, this association disappears after correction for confounding variables. CONCLUSIONS: We suggest that hyponatremia and hypokalemia have to be considered as a marker of poor health more than an independent fracture risk.

Type 2 diabetes affects bone cells precursors and bone turnover.

BACKGROUND: Here we study the effect of type 2 diabetes (T2DM) on bone cell precursors, turnover and cytokines involved in the control of bone cell formation and activity. METHODS: We enrolled in the study 21 T2DM women and 21 non diabetic controls matched for age and body mass index (BMI). In each subject we measured bone cell precursors, Receptor Activator of Nuclear Factor κB (RANKL), Osteoprotegerin (OPG), Sclerostin (SCL) and Dickoppf-1 (DKK-1) as cytokines involved in the control of osteoblast and osteoclast formation and activity, bone density (BMD) and quality trough trabecular bone score (TBS) and bone turnover. T2DM patients and controls were compared for the analyzed variables by one way ANOVA for Gaussian ones and by Mann-Whitney or Kruskal-Wallis test for non-Gaussian variables. RESULTS: RANKL was decreased and DKK-1 increased in T2DM. Accordingly, patients with T2DM have lower bone turnover compared to controls. BMD and TBS were not significantly different from healthy controls. Bone precursor cells were more immature in T2DM. However the number of osteoclast precursors was increased and that of osteoblasts decreased. CONCLUSIONS: Patients with T2DM have more immature bone cells precursors, with increased number of osteoclasts and decreased osteoblasts, confirming low bone turnover and reduced cytokines such as RANKL and DKK-1. BMD and TBS are not significantly altered in T2DM although, in contrast with other studies, this may be due to the match of patients and controls for BMI rather than age.

Effect of intermittent PTH treatment on plasma glucose in osteoporosis: A randomized trial.

We investigated the effect of bone turnover on glucose homeostasis, fat distribution and adipokine production during anabolic treatment with PTH. This is a parallel, randomized controlled, open label, trial. The randomization was done by computer generated tables to allocate treatments. Forty-six postmenopausal osteoporotic non-diabetic women were assigned to treatment with calcium and colecalcipherol with (24) or without (22) PTH 1-84. Patients were recalled after 3, 6, 12 and 18 months of treatment and markers of bone turnover, glucose metabolism, adipokine secretion and fat distribution were analyzed. Markers of bone turnover and adipokines were measured by ELISA. Glucose metabolism was evaluated by an oral glucose load test and insulin resistance and secretion were calculated. Fat and lean mass were evaluated by anthropometric measures. The effect of treatment on measured variables was analyzed by repeated measure test, and its effect on glucose was also evaluated by mediation analysis after correction for possible confounders. Twenty patients in the calcium and vitamin D groups and 19 in the group treated with PTH 1-84 completed the study. There were no significance adverse events. Treatment with PTH increases osteocalcin, both total (OC) and undercarboxylated (uOC), and decreases blood glucose, without influence on insulin secretion, resistance and pancreatic ß cell function. Treatment with PTH does not influence fat distribution and adipokine production. The results of the mediation analyses suggest a total effect of PTH on blood glucose, moderately mediated by OC and to a less extent by uOC. Here we suggest that treatment with PTH influences glucose metabolism partially through its effect on bone turnover, without influence on insulin secretion, resistance, pancreatic ß cell function and fat mass.

Hypovitaminosis D and organ damage in patients with arterial hypertension: a multicenter double blind randomised controlled trial of cholecalciferol supplementation (HYPODD) : study design, clinical procedures and treatment protocol.

INTRODUCTION: At this time, good quality randomized clinical trials assessing the effects of vitamin D supplementation on cardiometabolic outcomes are lacking in the international literature. AIM: To fill this gap, the Working Group on Vitamin D and Cardiorenal Disorders established jointly by the Italian Society of Hypertension (SIIA) and the Forum in Bone and Mineral Research conceived the HYPODD study (HYPOvitaminosis D and organ Damage). METHODS: HYPODD is a no-profit multicenter 12-month parallel-group double-blind placebo controlled randomized trial aiming to assess the effects of cholecalciferol supplementation on blood pressure control, antihypertensive drugs consumption and progression of target organ damage in patients with essential hypertension and 25-hydroxyvitamin D serum level lower than 20 ng/ml (vitamin D deficiency). HYPODD is coordinated by the European Society Excellence Center of Hypertension of Federico II University, Naples, and involves 12 academic institutions in Italy (Ancona, Milan, Padua, Perugia, Rome, Siena, Trieste, Turin, Udine, Varese, and Verona). RESULTS AND CONCLUSION: The HYPODD study has been registered at the Agenzia Italiana del Farmaco-Osservatorio sulla Sperimentazione Clinica del Farmaco (AIFA-OsSC) and EUDRACT sites (n° 2012-003514-14) and has been approved by the Ethical Committees of all the Centers involved in the study. The patients' recruitment is currently underway.

Prevalence of postmenopausal osteoporosis in Italy and validation of decision rules for referring women for bone densitometry.

We report the prevalence of osteoporosis, osteopenia, and fractures in a cohort of Italian women randomly recruited among the general population and validate the use of clinical guidelines in referring women for bone density testing. We enrolled in the study 995 healthy women (age range 45-92 years). A bone density test at the lumbar spine and femur was performed and a questionnaire on osteoporosis risk factors completed for all patients. The prevalence of osteoporosis was 33.67 %, that of osteopenia was 46.63, and 19.7 % were normal at bone density testing. Osteoporotic women were generally older and thinner, with a shorter period of estrogen exposure. The prevalence of fractures was 21.9 %, and fractured women had a lower bone density, were older, and had a longer postmenopausal period. Clinical guidelines for referring women for bone density testing performed poorly (the best performance was 68 %). This is the first study providing data on the prevalence of osteoporosis/osteopenia and of fractures in a cohort of healthy postmenopausal women. Known risk factors influence bone density and risk of fractures. The role of screening in detecting women with postmenopausal osteoporosis is far from optimal.

Energy metabolism and the skeleton: Reciprocal interplay.

The relation between bone remodelling and energy expenditure is an intriguing, and yet unexplained, challenge of the past ten years. In fact, it was only in the last few years that the skeleton was found to function, not only in its obvious roles of body support and protection, but also as an important part of the endocrine system. In particular, bone produces different hormones, like osteocalcin (OC), which influences energy expenditure in humans. The undercarboxylated form of OC has a reduced affinity for hydroxyapatite; hence it enters the systemic circulation more easily and exerts its metabolic functions for the proliferation of pancreatic ß-cells, insulin secretion, sensitivity, and glucose tolerance. Leptin, a hormone synthesized by adipocytes, also has an effect on both bone remodelling and energy expenditure; in fact it inhibits appetite through hypothalamic influence and, in bone, stimulates osteoblastic differentiation and inhibits apoptosis. Leptin and serotonin exert opposite influences on bone mass accrual, but several features suggest that they might operate in the same pathway through a sympathetic tone. Serotonin, in fact, acts via two opposite pathways in controlling bone remodelling: central and peripheral. Serotonin product by the gastrointestinal tract (95%) augments bone formation by osteoblast, whereas brain-derived serotonin influences low bone mineral density and its decrease leads to an increase in bone resorption parameters. Finally, amylin (AMY) acts as a hormone that alters physiological responses related to feeding, and plays a role as a growth factor in bone. In vitro AMY stimulates the proliferation of osteoblasts, and osteoclast differentiation. Here we summarize the evidence that links energy expenditure and bone remodelling, with particular regard to humans.