The chloride/phosphate ratio combined with alkaline phosphatase as a valuable predictive marker for primary hyperparathyroidism in Chinese individuals

The Ca∗Cl/P Ratio: A Novel and More Appropriate Screening Tool for Normocalcaemic or Overt Primary Hyperparathyroidism

OBJECTIVE

The main purpose of this study was to explore the diagnostic performance of the Ca∗Cl/P ratio for primary hyperparathyroidism (PHPT), especially normocalcaemic PHPT (NPHPT), to assist health care providers in making reliable and rapid clinical identifications.

METHODS

From January 1, 2013, to March 31, 2023, 230 PHPT patients, including 65 with NPHPT and 230 sex- and age-matched controls, were enrolled in this retrospective study. Differences between hypercalcaemic PHPT (HPHPT) and NPHPT and between them and their respective controls were analyzed. The diagnostic accuracy of the Ca∗Cl/P ratio, Ca/P ratio, Cl/P ratio and albumin-corrected calcium was assessed by the area under the receiver operating characteristic curve.

RESULTS

Compared with corresponding controls, NPHPT and HPHPT patients both had significantly higher Ca ∗ Cl/P ratios (271.64 ± 51.74 vs 192.71 ± 26; 419.91 ± 139.11 vs 199.14 ± 36.75, P < .001). In the overall cohort, the ROC-AUC of the Ca∗Cl/P ratio (0.964, 95% CI = 0.943-0.979) for diagnosis of PHPT patients was superior to albumin-corrected calcium (0.959, 95% CI = 0.934-0.973), the Ca/P ratio (0.956, 95% CI = 0.934-0.973), and the Cl/P ratio (0.923, 95% CI = 0.895-0.946). A Ca ∗ Cl/P ratio above 239.17 mmol/L, with sensitivity (0.952), specificity (0.922), PPV (0.924), NPV (0.951) and accuracy (0.937), can distinguish PHPT patients from healthy individuals. Furthermore, the Ca ∗ Cl/P ratio yielded a sensitivity of 0.831, specificity of 0.938, PPV of 0.931, NPV of 0.847 and accuracy of 0.885 for NPHPT.

CONCLUSION

The Ca∗Cl/P ratio provides excellent diagnostic power for diagnosis of PHPT, especially NPHPT.

Hungry bone syndrome in peritoneal dialysis patients after parathyroid surgery

Secondary hyperparathyroidism (SHPT) is a common complication of end-stage kidney disease (ESKD). Hungry bone syndrome (HBS) occurs frequently in patients on maintenance dialysis receiving parathyroidectomy for refractory SHPT. However, there is scanty study investigating the clinical risk factors that predict postoperative HBS, and its outcome in peritoneal dialysis (PD) patients. We conducted a single-center retrospective study to analyze 66 PD patients who had undergone parathyroidectomy for secondary hyperparathyroidism at Chang Gung Memorial Hospital between 2009 and 2019. The patients were stratified into two groups based on the presence (n=47) or absence (n=19) of HBS after parathyroidectomy. Subtotal parathyroidectomy was the most common surgery performed (74.2%), followed by total parathyroidectomy with autoimplantation (25.8%). Pathological examination of all surgical specimens revealed parathyroid hyperplasia (100%). Patients with HBS had lower levels of postoperative nadir corrected calcium, higher alkaline phosphate (ALP), and higher potassium levels compared with patients without HBS (all P<0.05). A multivariate logistic regression model confirmed that lower preoperative serum calcium level (OR 0.354, 95% CI 0.133-0.940, P=0.037), higher ALP (OR 1.026, 95% CI 1.008-1.044, P=0.004), and higher potassium level (OR 6.894, 95% CI 1.806-26.317, P=0.005) were associated with HBS after parathyroidectomy. Patients were followed for 58.2±30.8 months after the surgery. There was no significant difference between HBS and non-HBS groups in persistence (P=0.496) or recurrence (P=1.000) of hyperparathyroidism. The overall mortality rate was 10.6% with no significant difference found between both groups (P=0.099). We concluded that HBS is a common complication (71.2%) of parathyroidectomy for SHPT and should be managed appropriately.

Diagnostic performance of the calcium/phosphate ratio for primary hyperparathyroidism in southwest China

BACKGROUND

The diagnosis of primary hyperparathyroidism (PHPT) remains a challenge because of increased asymptomatic PHPT or patients with normocalcaemic PHPT (NPHPT). In addition, some primary hospitals in China have no equipment to measure parathyroid hormone (PTH) levels. Therefore, an additional, simple, and inexpensive laboratory biochemical marker is urgently needed. The calcium/phosphate (Ca/P) ratio and chloride/phosphate (Cl/P) ratio have been proposed as suitable tools to diagnose PHPT in Europe; however, the Ca/P ratio has never been tested in China. We aimed to conduct a confirmatory study to explore the diagnostic performance of the Ca/P ratio for PHPT in China.

METHODS

From January 2015 to December 2020, a total of 155 patients who underwent parathyroidectomy (143 PHPT patients and 12 NPHPT patients) and 153 controls were enrolled in this single-center , retrospective study. Serum calcium, phosphate, parathyroid hormone, 25-hydroxyvitamin vitamin D (25(OH) vitamin D), chloride, alanine transaminase (ALT), aspartate aminotransaminase (AST), estimated glomerular filtration rate (eGFR), and creatinine levels were recorded for all the study participants. Pairwise comparisons were made between groups, and the diagnostic performance of the Ca/P ratio was determined using receiver-operating characteristic (ROC) analysis.

RESULTS

Patients with PHPT had a higher Ca/P ratio than controls (P < 0.001). A Ca/P ratio above 2.94 with a sensitivity of 95.5% and specificity of 98.7% can distinguish PHPT patients from healthy individuals. This index was positively correlated with the PTH level (r = 0.875, P < 0.001).

CONCLUSION

The Ca/P ratio is an ideal and inexpensive indicator for diagnosing PHPT in China when using a cut-off value of 2.94.

Normocalcemic and Normohormonal Primary Hyperparathyroidism: Laboratory Values and End-Organ Effects

OBJECTIVE

Variants of primary hyperparathyroidism (pHPT), described as normocalcemic (NC) and normohormonal (NH), can confuse the diagnosis of classic pHPT.

DATA SOURCES

A MEDLINE search was performed for variants of pHPT using the PubMed database (last queried October 2019).

REVIEW METHODS

The search was restricted to articles published after 1960 that were specific to humans. Studies were included in our analysis if laboratory values and incidence of end-organ involvement were reported for NCpHPT and NHpHPT variants. The search returned 189 articles; 27 additional studies were identified and included for a total of 216. Non-English-language studies were excluded. Abstracts were screened, full-text articles were then assessed, and 82 articles were excluded. Data were pooled using a random-effects model in studies that compared NC or NH pHPT to classic pHPT. Comparative laboratory values are presented.

CONCLUSION

This analysis compares NCpHPT and NHpHPT to classic pHPT. Nephrolithiasis was 21.7% (NCpHPT), 15.9% (classic pHPT), and 25.4% (NHpHPT). Decreased bone mineral density was 49.7% (NCpHPT), 39.7% (classic pHPT), and 40.3% (NHpHPT). Fractures in the NCpHPT group were not significantly different from the classic pHPT. Hypertension in the NCpHPT group was significantly less than classic pHPT (odds ratio, 0.59; 95% CI, 0.40-0.88).

IMPLICATIONS FOR CLINICAL PRACTICE

This information may serve to inform clinicians of the laboratory subtleties of these variants that are being seen with greater frequency in contemporary practice.

The Utility of the Cl:PO4 Ratio in Patients With Variant Versions of Primary Hyperparathyroidism

OBJECTIVE

To determine the significance and impact of additional chloride testing as part of a diagnostic laboratory test battery for borderline primary hyperparathyroidism (pHPT).

STUDY DESIGN

Retrospective database review of parathyroidectomy patients.

SETTING

A tertiary care, academic health sciences center.

SUBJECTS AND METHODS

Patients referred to a head and neck endocrine clinic for evaluation and treatment for pHPT.

RESULTS

After exclusions, there were a total of 226 patients who underwent parathyroidectomy for primary hyperparathyroidism with the requisite preoperative and postoperative labs. Seventy-seven additional patients who had a thyroid operation for a nonmalignant cause were included as controls. Of the 303 total patients, 166 had normal calcium levels (<10.4 mg/dL), and 54 (32.5%) also exhibited hyperchloremia (>106 mmol/L). Of the 47 patients with normal calcium and parathyroid hormone (PTH) levels (<88 pg/mL), 6 (12.8%) had hyperchloremia, and of the 118 patients with normocalcemic pHPT, 48 (40.7%) were hyperchloremic. The area under the curve for the Cl:PO4 was 0.712. When using a cutoff of 33, the reported sensitivity and specificity of the curve were 58.4% and 28.6%, respectively.

CONCLUSION

The Cl:PO4 ratio was a moderately sensitive test for the diagnosis of the borderline variants of primary hyperparathyroidism. The Ca:PO4 ratio was superior to the Cl:PO4 ratio. Our data also showed the superiority of preoperative calcium and ionized calcium over PTH when predicting the presence of pHPT.

Severe, Symptomatic Hypocalcemia due to Denosumab Administration: Treatment and Clinical Course

Denosumab is a receptor activator of nuclear factor kappa-B (RANK) ligand inhibitor used in the treatment of osteoporosis. Blockade of RANK ligand prevents osteoclastic resorption of bone, but in doing so impairs the parathyroid hormone (PTH)-driven maintenance of serum calcium. A subsequent elevation of PTH remains active at sites other than bone, potentially lowering serum phosphate by inhibiting proximal tubular reabsorption. We present 2 patients who developed severe, symptomatic hypocalcemia after administration of denosumab. These patients provide an opportunity to describe the clinical course and treatment, including the need to consider a continuous calcium infusion, of severe, symptomatic hypocalcemia caused by denosumab.