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Background: 25-hydroxyvitamin D (25OHD) levels much influence parathyroid hormone levels and bone disease in primary hyperparathyroidism (PHPT). With the emergence of the normocalcaemic PHPT (NCPHPT), repletion of the 25OHD level to rule out secondary hyperparathyroidism (SHPT) is essential. This may delay the diagnosis of PHPT, and a diagnostic tool like parathyroid function index (PF index) may help in the early diagnosis. Methods: The biochemical and hormonal profiles of 52 patients with PHPT were analysed and compared with first description in 1990. Patients were grouped based on symptoms and albumin-corrected serum calcium levels. Those with normocalcaemia were subgrouped into those with and without 25OHD deficiency. Data were extracted from the hospital's electronic medical records to find subjects with SHPT and normal controls and calcium-to-phosphate ratio (C/P ratio) and the PF index were calculated. Receiver operating characteristic curves to decide the cut-off values that help in identifying PF index and C/P ratio between various subgroups. Results: Sixty-two per cent (32/52) were asymptomatic, 40% (21/52) normocalcaemic, amongst which 48% (10/21) had normal 25OHD levels. Across all categories, the PF index was more sensitive, specific and superior compared to the C/P ratio in the diagnosis of PHPT (P = 0·02), NCPHPT (P = 0·03) or SHPT (P = 0·0001). PF index (>25·8) was more sensitive (90%), specific (96.51%), compared to C/P ratio (>0·211) (P = 0·04) in differentiating NCPHPT from SHPT. Conclusions: The prevalence of asymptomatic PHPT and NCPHPT is on the rise. PF index helps distinguish NCPHPT from SHPT minimising the time required for confirming the diagnosis post-25OHD repletion.

Background: 25-hydroxyvitamin D (25OHD) levels much influence parathyroid hormone levels and bone disease in primary hyperparathyroidism (PHPT). With the emergence of the normocalcaemic PHPT (NCPHPT), repletion of the 25OHD level to rule out secondary hyperparathyroidism (SHPT) is essential. This may delay the diagnosis of PHPT, and a diagnostic tool like parathyroid function index (PF index) may help in the early diagnosis. Methods: The biochemical and hormonal profiles of 52 patients with PHPT were analysed and compared with first description in 1990. Patients were grouped based on symptoms and albumin-corrected serum calcium levels. Those with normocalcaemia were subgrouped into those with and without 25OHD deficiency. Data were extracted from the hospital's electronic medical records to find subjects with SHPT and normal controls and calcium-to-phosphate ratio (C/P ratio) and the PF index were calculated. Receiver operating characteristic curves to decide the cut-off values that help in identifying PF index and C/P ratio between various subgroups. Results: Sixty-two per cent (32/52) were asymptomatic, 40% (21/52) normocalcaemic, amongst which 48% (10/21) had normal 25OHD levels. Across all categories, the PF index was more sensitive, specific and superior compared to the C/P ratio in the diagnosis of PHPT (P = 0·02), NCPHPT (P = 0·03) or SHPT (P = 0·0001). PF index (>25·8) was more sensitive (90%), specific (96.51%), compared to C/P ratio (>0·211) (P = 0·04) in differentiating NCPHPT from SHPT. Conclusions: The prevalence of asymptomatic PHPT and NCPHPT is on the rise. PF index helps distinguish NCPHPT from SHPT minimising the time required for confirming the diagnosis post-25OHD repletion. [ABSTRACT FROM AUTHOR]

Abstract Background Patients with primary hyperparathyroidism (PHPT) may be asymptomatic, and some may present with normocalcemic PHPT (NPHPT). Patients with vitamin D deficiency may also be asymptomatic, with normal calcium and elevated PTH concentrations. These latter patients are usually diagnosed with vitamin D deficiency-induced secondary hyperparathyroidism (VD-SHPT). Therefore, it is very difficult to distinguish PHPT and NPHPT from VD-SHPT based on calcium or PTH concentrations in clinical settings. In this case-control study, we aimed to verify the diagnostic power of a new parathyroid function index (PFindex = Ca*PTH/P). Methods This study enrolled 128 patients with surgically and pathologically confirmed PHPT, including 36 with NPHPT, at a hospital in West China between January 2009 and September 2017. Thirty-seven patients with VD-SHPT and 45 healthy controls were selected from the population of a cross-sectional epidemiological study as the SHPT and healthy groups, respectively. We used the PFindex to describe the characteristics of PHPT, NPHPT, and VD-SHPT.. Differences between the four groups were compared, and a receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic power of PFindex. Results The PHPT group had the highest PFindex (454 ± 430), compared to the other three groups (NPHPT: 101 ± 111; SHPT: 21.7 ± 6.38; healthy: 12.2 ± 2.98, all p 34 to differentiate NPHPT from VD-SHPT yielded the highest positive likelihood ratio and lowest negative likelihood ratio. Conclusion The PFindex provided excellent diagnostic power for the differentiation of NPHPT from VD-SHPT. This simple tool may be useful for guiding timely decision-making processes regarding the initiation of vitamin D treatment or surgery for PHPT.

Background: Patients with primary hyperparathyroidism (PHPT) may be asymptomatic, and some may present with normocalcemic PHPT (NPHPT). Patients with vitamin D deficiency may also be asymptomatic, with normal calcium and elevated PTH concentrations. These latter patients are usually diagnosed with vitamin D deficiency-induced secondary hyperparathyroidism (VD-SHPT). Therefore, it is very difficult to distinguish PHPT and NPHPT from VD-SHPT based on calcium or PTH concentrations in clinical settings. In this case-control study, we aimed to verify the diagnostic power of a new parathyroid function index (PFindex = Ca*PTH/P). Methods: This study enrolled 128 patients with surgically and pathologically confirmed PHPT, including 36 with NPHPT, at a hospital in West China between January 2009 and September 2017. Thirty-seven patients with VD-SHPT and 45 healthy controls were selected from the population of a cross-sectional epidemiological study as the SHPT and healthy groups, respectively. We used the PFindex to describe the characteristics of PHPT, NPHPT, and VD-SHPT.. Differences between the four groups were compared, and a receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic power of PFindex. Results: The PHPT group had the highest PFindex (454 ± 430), compared to the other three groups (NPHPT: 101 ± 111; SHPT: 21.7 ± 6.38; healthy: 12.2 ± 2.98, all p < 0.001). A PFindex cut-off value of 34 yielded sensitivity and specificity rates of 96.9 and 97.6% and of 94.4 and 94.6% for the diagnoses of PHPT and NPHPT, respectively. The use of a PFindex > 34 to differentiate NPHPT from VD-SHPT yielded the highest positive likelihood ratio and lowest negative likelihood ratio. Conclusion: The PFindex provided excellent diagnostic power for the differentiation of NPHPT from VD-SHPT. This simple tool may be useful for guiding timely decision-making processes regarding the initiation of vitamin D treatment or surgery for PHPT. [ABSTRACT FROM AUTHOR]