Comparison between paricalcitol versus cinacalcet therapy in the management of secondary hyperparathyroidism among prevalent hemodialysis patients

Introduction: Secondary hyperparathyroidism (SHPT) is one of the components of chronic kidney disease–mineral bone disorder (CKD-MBD) with significant contribution to the morbidity and mortality among prevalent hemodialysis (HD) patients. Objectives: This multi-centric experience study aims to compare the effectiveness of intravenous (IV) paricalcitol versus oral cinacalcet and oral cinacalcet plus oral alfacalcidol as treatment regimens of SHPT among chronic HD patients. Patients and Methods: This is a retrospective observational cohort study, in which 130 prevalent HD patients with SHPT was recruited from three main HD centres of Aljouf region in Saudi Arabia. Patients were divided into three groups; group I (50) HD patients were treated by IV paricalcitol, group II (50) HD patients who received oral cinacalcet plus oral alfacalcidol, group III (30) HD patients were on oral cinacalcet. Serum intact parathyroid hormone (iPTH), calcium (Ca), phosphorus (Po4) and alkaline phosphatase (ALP) tests were assessed at 0, 3, 6, and 9 months. Results: A total of 130 (61 (47%) females, (53%) 69 males) HD patients with mean age 56.30 ± 19.1 years, and with mean HD duration of 4.86±4.15 years were enrolled in the study. The mean of iPTH is significantly reduced in all studied groups (P<0.001). Mean Δchanges in iPTH concentration in groups I, II, III were -242.11±148.75, -225.54±153.91 and -254.83±275.17 respectively; P>0.05) with statistical non-significant differences. Increase of Ca×Po4 with paricalcitol group as mean ΔChange in (Ca×PO4) was in the groups I, II, III (15.39±9.46, 1.97±11.74, -2.89±9.37) respectively (P<0.001). Our study showed a significant increase in serum phosphorus from the baseline in patients of group II. Conclusion: IV paricalcitol based regimen assumed to be equally effective in suppressing SHPT in HD patients when compared to the combination of oral cinacalcet with oral alfacalcidol or treatment with oral cinacalcet alone.

Measurement of serum intact parathyroid hormone concentration 1 day after total thyroidectomy to assess risk of permanent hypoparathyroidism

Objective This study was performed to assess the clinical value of measuring the intact parathyroid hormone (iPTH) concentration 1 day after total thyroidectomy to estimate the occurrence of permanent hypoparathyroidism (pHPP). Methods Data of 546 patients who underwent total thyroidectomy from February 2008 to December 2018 were retrospectively analyzed. Calcium and iPTH concentrations were collected preoperatively and at 1 day and 6 months postoperatively. Logistic regression was used to analyze the correlation between clinical indexes and postoperative pHPP. Results Of the 546 patients, 22 (4.03%) developed pHPP. Multivariate analysis showed that the iPTH and serum calcium concentrations measured 1 day after surgery were independent predictors of the risk of pHPP. An iPTH concentration of 5.51 pg/mL measured 1 day postoperatively was used as the cut-off value, and the area under the curve was 0.956. The risk of pHPP was identified with a sensitivity of 100%, specificity of 85.1%, positive predictive value of 22%, and negative predictive value of 100%. Conclusions The iPTH concentration measured 1 day after total thyroidectomy is closely related to the occurrence of pHPP postoperatively and is an independent predictive risk factor. The postoperative iPTH concentration can be helpful in identifying patients at risk for developing pHPP.

Study on the Relationship of 25-hydroxyvitamin D and Intact Parathyroid Hormone in Chinese Young Adults

Background : Vitamin D plays an important role in bone health and other diseases, however, there is no consensus over the optimal serum 25-hydroxyvitamin D (25(OH)D) concentration. Many studies defined a level of serum 25(OH)D at which serum intact parathyroid hormone (iPTH) levels decreased and reached a plateau might be the optimal status for vitamin D sufficiency. This study was performed to study the relationship between 25(OH)D concentration and intact parathyroid hormone (iPTH) concentration in the Chinese non-clinical young population aged 18-44y. Methods : The serum samples of young adults aged 18-44 years old were selected from the established serum bank of Chinese Chronic Diseases and Nutrition Survey (CCDNS, 2015-2018). The serum 25(OH)D concentration was determined by high performance liquid chromatography tandem mass spectrometer, and the iPTH was determined by electronic chemiluminescence method. The relationship of 25(OH)D and iPTH were analyzed by partial correlation analysis, and the threshold of 25(OH)D was analyzed by locally weighted scatter plot smoothing method after adjusting the iPTH by age, season of blood draw, BMI, waist, sex and latitude. Results : 623 serum samples (293 male, 330 female) of 25(OH)D concentration and iPTH concentration were analyzed. Significant higher 25(OH)D concentration was found in male than female. And the samples from the southern China had higher 25(OH)D concentration than those from the northern China. Samples from autumn had higher 25(OH)D concentration than those from spring and winter. The inversely relationship between 25(OH)D concentration and iPTH concentration was observed when the 25(OH)D was below 17.6 ng/mL for both sexes. The threshold for male was 16.2 ng/mL and it was 25.6 ng/mL for female. Conclusions : The threshold and the relationship between 25(OH)D and iPTH differs by sex among Chinese young adults aged 18-44y. Further study is needed to evaluate the sex-specific ranges of optimal vitamin D. Trial registration : Not applicable.

Study on the Relationship of 25-hydroxyvitamin D and Intact Parathyroid Hormone in Chinese Adults

Background:Vitamin D plays an important role in bone health and other diseases, however, there is no consensus over the optimal serum 25-hydroxyvitamin D (25(OH)D) concentration. Many studies consider that the 25(OH)D concerntration which maximally inhibit serum intact parathyroid hormone (iPTH) might be the optimal status for vitamin D sufficiency. This study was performed to study the relationship between 25(OH)D concentration and intact parathyroid hormone (iPTH) concentration in the Chinese non-clinical population aged 18-44y. Methods: The serum samples of adults aged 18-44 years old were selected from the established serum bank of Chinese Chronic Diseases and Nutrition Survey (CCDNS, 2015-2018). The serum 25(OH)D concentration was determined by high performance liquid chromatography tandem mass spectrometer, and the iPTH was determined by electronic chemiluminescence method. The relationship of 25(OH)D and iPTH were analyzed by correlation analysis, segmented linear regression and the confidence interval was determined by bootstrap method. Results: 623 serum samples (293 male, 330 female) of 25(OH)D concentration and iPTH concentration were analyzed. Significant higher 25(OH)D concentration was found in male than female. And the samples from the southern China had higher 25(OH)D concentration than those from the northern China. Samples from autumn had higher 25(OH)D concentration than those from spring and winter. The inversely relationship between 25(OH)D concentration and iPTH concentration was observed in both male and female. The concentration of 25(OH)D was 19.2 (10.1-27.2) ng/mL (P=0.02) when iPTH entered the plateau in women and no plateau for iPTH was found in men. Conclusions: The relationship between 25(OH)D and iPTH differs by sex among Chinese adults aged 18-44y. Further study is needed to evaluate the sex-specific ranges of optimal vitamin D. Trial registration: Not applicable. Keywords: 25-hydroxyvitamin D; parathyroid hormone; plateau; Chinese adults

Hemodialysis patients with low serum parathyroid hormone levels have a poorer prognosis than those with secondary hyperparathyroidism

Background: Low serum parathyroid hormone (PTH) level and secondary hyperparathyroidism (SHPT) are very common in hemodialysis patients. However, the outcomes of patients with low PTH level or SHPT have not been carefully compared. Therefore, in the present study, we compared the outcomes of hemodialysis patients with low PTH level or SHPT. Methods: This was a multi-center, prospective, cohort study of 647 patients. The patients were recruited between 1 September 2016 and 1 January 2017 and followed until 31 December 2018. The participants were allocated to a low PTH group [serum intact PTH (iPTH) concentration < 60 pg/ml] and an SHPT group (iPTH ⩾ 600 pg/ml) according to their mean iPTH concentration across the entire observation period, and the outcomes were compared between these groups. The primary outcome was a composite outcome, which comprised all-cause mortality, non-fatal acute myocardial infarction, non-fatal acute stroke, and acute heart failure. Results: A total of 197 hemodialysis patients were allocated to the two groups: 87 with low PTH level and 110 with SHPT; 450 patients with time-averaged iPTH concentrations of 60–600 pg/ml were excluded. Kaplan–Meier analysis of the composite endpoint revealed a significant difference between participants with low PTH level and those with SHPT ( p = 0.002). Cox multiple regression showed that participants with low PTH level had a higher incidence of the composite endpoint than those with SHPT (relative risk: 1.337, 95% confidence interval: 1.059–1.688). Conclusion: Hemodialysis patients with low PTH level had a higher incidence of mortality and non-fatal cardiovascular events than those with SHPT, irrespective of whether the participants were age-matched.

Episodic secretion of parathyroid hormone in the dog

This study was designed to determine whether parathyroid hormone (PTH) is secreted episodically, to characterize any such rhythms, and to see whether the rhythms can be altered by stimulating PTH secretion using constant hypocalcemia. We collected blood samples at 1-min intervals for 1 h from the precava or postcava of conscious dogs during normocalcemia or induced, constant hypocalcemia. In two anesthetized normocalcemic dogs we catheterized a caudal thyroid vein and collected all the effluent blood in 1-min fractions. Immunoreactive PTH (IPTH) concentrations were determined in quadruplicate, and the results were subjected to spectral analysis. In both the precava and postcava of normocalcemic dogs, there were regular oscillations in IPTH levels with a period of 12 min (range, 10–15 min) and a +/- 14% variation about the overall mean. Although significant two- to fourfold changes in IPTH levels still occurred during constant hypocalcemia, there was no significant rhythmicity. Significant cycles in IPTH concentration (mean 8.4-min period) were observed in thyroid venous effluent plasma during normocalcemia, confirming that the phenomenon represented episodic secretion that was not affected by pentobarbital anesthesia.

The “calcium clamp”: effect of constant hypocalcemia on parathyroid hormone secretion

This report describes acute studies of parathyroid hormone (PTH) secretion and metabolism in conscious dogs, performed with a new technique, the “calcium clamp.” Bolus injections and graded infusions of either calcium (Ca) or EGTA, respectively, increase or decrease plasma Ca to desired levels in 1–2 min; rapid determination of plasma Ca permits feedback control of the infusion rates to maintain the desired Ca concentration for prolonged periods. Using this technique, we have examined the effect in five dogs of a sustained (1 h) decrease in plasma Ca from 9.6 to 7.6 mg/dl on the secretion of PTH. Plasma immunoreactive PTH (IPTH) concentration in precaval blood increased within 1 min, peaked at 4–10 min (greater than 5 times control), but thereafter declined gradually to 57% of the maximum at 60 min, despite ongoing and constant hypocalcemia. Abrupt restoration of normocalcemia caused IPTH levels to decrease with an apparent half-time of 3.0 +/- 0.3 min (mean +/- SE). Thus, external feedback-regulated control of plasma Ca is possible in experimental animals. IPTH concentrations decline from the maximum during constant hypocalcemia, a new observation that suggests that PTH secretion and/or metabolism are altered progressively by the hypocalcemia.