Serum parathyroid hormone levels and renal handling of phosphorus in patients with chronic renal disease

In eight patients with advanced renal insufficiency (inulin clearance 1.4-9.1 ml/min), concentrations of serum calcium (S[Ca]) and phosphorus (S[P]) were maintained normal (S[Ca] > 9.0 mg/100 ml, (S[P] < 3.5 mg/100 ml) for at least 20 consecutive days with phosphate binding antacids and oral calcium carbonate. The initial serum levels of immunoreactive parathyroid hormone (S-PTH) were elevated in three (426-9230 pg/ml), normal in four (one after subtotal parathyroidectomy), and not available in one. The initial fractional excretion of filtered phosphorus was high in all and ranged from 0.45-1.05. Following sustained normo-calcemia and normo-phosphatemia, S-PTH was reduced below control levels in all patients; being normal in six and elevated in two. decreased below control levels in all patients; it remained high in six (of which five had normal S-PTH) and was normal in two (of which one had elevated S-PTH). The observed relationship between S-PTH and could either reflect the inability of the radioimmunoassay for PTH employed to measure a circulating molecular species of PTH which was present in which case the actual levels of S-PTH were higher than those measured, and/or it could be indicative of the presence of additional important factor(s) (other than S-PTH) which inhibit tubular reabsorption of phosphorus in advanced chronic renal failure. © 1972 by The Endocrine Society

Association between pruritus and serum concentrations of parathormone, calcium and phosphorus in hemodialysis patients.

Chronic renal disorders have a progressive course in most cases, and finally result in end-stage renal disease (ESRD). Hemodialysis (HD) is one of the mainstays in the treatment of these patients. Disturbance in calcium (Ca) and phosphorus (P) metabolism and alteration of serum levels of parathormone (PTH) are observed in these patients. One of the most common cutaneous manifestations in patients on HD is pruritus. The aim of this study is to evaluate the association between pruritus and serum concentrations of Ca, P and PTH in patients with chronic renal disease. This analytic, descriptive, cross-sectional study was performed on 120 patients on HD at the Fifth-Azar Hospital in Gorgan, Iran, in 2010. Information related to the patients, including age, gender, pruritus, time of pruritus and duration on dialysis, was extracted from questionnaires. Serum concentrations of intact PTH, Ca and P were measured. Data were analyzed by the chi-square test and SPSS-16 software. A P-value less than 0.05 was considered statistically significant. Among the 120 study patients, 50% were male and the mean age (±SD) was 49 ± 12.3 years. Sixty percent of the patients had pruritus, of whom 33.3% had PTH levels above the normal range. Among the 40% of the patients who did not have pruritus, 39.6% had PTH levels higher than the normal levels. The mean serum Ca and P levels were 8.44 ± 1.65 mg/dL and 5.48 ± 1.81 mg/dL, respectively. The mean (±SD) Ca-P product was 55.46 ± 47.16 and the mean PTH concentration was 274.34 ± 286.53 pg/mL. No significant association was found between pruritus and age, sex, serum PTH and P levels as well as Ca-P product. However, the association between serum Ca levels and pruritus was significant (P = 0.03). Our study showed that most patients with pruritus had serum Ca levels in the abnormal range (lower or higher), and there was no significant correlation between serum iPTH level and pruritis. Thus, good control of serum Ca levels is important to reduce pruritus in these patients

Retinal micro-vascular and aortic macro-vascular changes in postmenopausal women with primary hyperparathyroidism

Aim of the study was to evaluate the micro and macro-vascular changes in patients with primary hyperparathyroidism (PHPT) compared to controls. 30 postmenopausal PHPT women (15 hypertensive and 15 normotensive) and 30 normotensive controls underwent biochemical evaluation of mineral metabolism and measurements of arterial stiffness by 24 hour ambulatory blood pressure monitoring. Retinal microcirculation was imaged by a Retinal Vessel Analyzer. PHPT patients also underwent bone mineral density measurements and kidney ultrasound. PHPT patients had higher mean calcium and parathyroid hormone values compared to controls. Evaluating macro-vascular compartment, we found higher values of 24 hours-systolic, diastolic blood pressure, aortic pulse wave velocity (aPWV) and aortic augmentation index (Aix) in hypertensive PHPT, but not in normotensive PHPT compared to controls. The eye examination showed narrowing arterial and venular diameters of retinal vessels in both hypertensive and normotensive PHPT compared to controls. In hypertensive PHPT, 24 hours systolic blood pressure was associated only with parathyroid hormone (PTH) levels (beta = 0.36, p = 0.04). aPWV was associated with retinal diameter (beta = −0.69, p = 0.003), but not with PTH. Retinal artery diameter was associated with PTH (beta = −0.6, p = 0.008). In the normotensive PHPT, only PTH was associated with retinal artery diameter (beta = −0.60, p = 0.01) and aortic AIx (beta = 0.65, p = 0.02). In conclusion, we found macro-vascular impairment in PHPT and that micro-vascular impairment is negatively associated with PTH, regardless of hypertension in PHPT

Influence of vitamin D on biomechanical microstructure and properties of patients with hip fracture.

Valorar niveles séricos de 25-hidroxivitamina D -25(OH)D-, hormonas con influencia sobre el metabolismo óseo (parathormona -PTH- y factor de crecimiento insulínico -IGF-I-), marcadores de remodelado óseo (MRO) (telopéptido carboxilo-terminal del colágeno tipo I -β-CTX- y propéptido aminoterminal del procolágeno tipo I -PINP-), densidad mineral ósea (DMO), microestructura y biomecánica de cuello de fémur, en pacientes con fractura de cadera osteoporótica (OP) vs. pacientes artrósicos (OA). Material y métodos: Estudio observacional transversal de 29 pacientes OP y 14 OA, edad ≥50 años. Cuantificamos niveles séricos hormonales y MRO (inmunoensayo), DMO de cadera (DXA), microestructura (micro-CT) y biomecánica (ensayos de compresión uniaxial, sistema IGFA). Análisis estadístico (SPSS 20.0.) Resultados: Los pacientes OP presentaron niveles inferiores de 25(OH)D (p=0,02) y DMO de cadera (p<0,05), y superiores de PTH (p=0,029) y de β-CTX (p=0,04). Los niveles de 25(OH)D se correlacionaron positivamente con IGF-I (p=0,04) y negativamente con β-CTX (p=0,003). Los valores de PTH se correlacionaron negativamente con DMO de cadera (p=0,0005) y positivamente con la separación trabecular (Tb.Th) (p=0,006). Los pacientes con niveles de 25(OH)D <20 ng/mL presentaron niveles mayores de β-CTX (p=0,006), menores de IGF-I (p=0,007) y Tb.Th (p=0,04). Conclusiones: Los niveles de vitamina D son bajos en población anciana, sobre todo en pacientes con fractura de cadera osteoporótica. Además, en estos pacientes existen niveles elevados de PTH y MRO y descendidos de DMO. Los pacientes cuyos niveles de 25(OH)D son inferiores a 20 ng/mL presentan un remodelado óseo más elevado, con menores niveles de IGF-I y alteraciones de la estructura ósea (Tb.Th) que puedan estar en relación con un mayor riesgo de fracturas.To assess serum levels of 25-hydroxyvitamin D-25 (OH) D-hormones with influence on bone metabolism (parathormone -PTH- and insulin-like growth factor (IGF)-I), bone remodeling markers (BRM) (carboxy-terminal telopeptide of collagen type I-β-CTX- and amino-peptide pro-peptide of procollagen type I -PINP), bone mineral density (BMD), microstructure and biomechanics of the femoral neck, in patients with osteoporotic hip fracture (OH) versus arthritic patients (OA). Material and methods: A cross-sectional observational study of 29 OH and 14 OA, age ≥50 years. We quantified hormonal serum levels and BRM (immunoassay), hip BMD (DXA), microstructure (micro-CT) and biomechanics (uniaxial compression tests, IGFA system). Analysis (SPSS 20.0.) Results: OH patients had lower levels of 25(OH)D (p=0.02) and hip BMD (p<0.05), and higher PTH (p=0.029) and β-CTX (p=0.04). Levels of 25(OH)D correlated positively with IGF-I (p=0.04) and negatively with β-CTX (p=0.003). The PTH values were correlated negatively with hip BMD (p=0.0005) and positively with trabecular thickness (TbTh) (p=0.006). Patients with 25(OH)D <20 ng/mL presented higher levels of β-CTX (p=0.006), lower IGF-I (p=0.007) and TbTh (p=0.04). Conclusions: Vitamin D levels are low in the elderly population, especially in patients with osteoporotic hip fracture. These patients also presented raised levels of PTH and BRM and descended from BMD. Patients whose 25(OH)D levels are below 20 ng/mL present higher bone remodeling, with lower levels of IGF-I and alterations of the bone structure (TbTh) that may be linked to a greater risk of fractures

Parathyroid hormone secretion is controlled by both ionized calcium and phosphate during exercise and recovery in men

Context: The mechanism by which PTH is controlled during and after exercise is poorly understood due to insufficient temporal frequency of measurements. Objective: The objective of the study was to examine the temporal pattern of PTH, PO4, albumin-adjusted calcium, and Ca2+ during and after exercise. Design and Setting: This was a laboratory-based study with a crossover design, comparing 30 minutes of running at 55%, 65%, and 75% maximal oxygen consumption, followed by 2.5 hours of recovery. Blood was obtained at baseline, after 2.5, 5, 7.5, 10, 15, 20, 25, and 30 minutes of exercise, and after 2.5, 5, 7.5, 10, 15, 20, 25, 30, 60, 90, and 150 minutes of recovery. Participants: Ten men (aged 23 ± 1 y, height 1.82 ± 0.07 m, body mass 77.0 ± 7.5 kg) participated. Main Outcome Measures: PTH, PO4, albumin-adjusted calcium, and Ca2+ were measured. Results: Independent of intensity, PTH concentrations decreased with the onset of exercise (−21% to −33%; P ≤ .001), increased thereafter, and were higher than baseline by the end of exercise at 75% maximal oxygen consumption (+52%; P ≤ .001). PTH peaked transiently after 5–7.5 minutes of recovery (+73% to +110%; P ≤ .001). PO4 followed a similar temporal pattern to PTH, and Ca2+ followed a similar but inverse pattern to PTH. PTH was negatively correlated with Ca2+ across all intensities (r = −0.739 to −0.790; P ≤ .001). When PTH was increasing, the strongest cross-correlation was with Ca2+ at 0 lags (3.5 min) (r = −0.902 to −0.950); during recovery, the strongest cross-correlation was with PO4 at 0 lags (8 min) (r = 0.987–0.995). Conclusions: PTH secretion during exercise and recovery is controlled by a combination of changes in Ca2+ and PO4 in men