Incidence of secondary hyperparathyroidism among postmenopausal women with end-stage knee osteoarthritis

Underdiagnosis of primary hyperparathyroidism in patients with osteoarthritis undergoing arthroplasty

BACKGROUND

Primary hyperparathyroidism (HPT) is commonly underdiagnosed and undertreated. Joint pain is a nonspecific symptom associated with osteoarthritis or primary HPT. We hypothesize that patients treated for osteoarthritis are underdiagnosed with primary HPT.

METHODS

Adult patients diagnosed with hip/knee osteoarthritis at the Medical College of Wisconsin from January 2000 to October 2020 were queried. Patients with a calcium level drawn within 1 year of diagnosis of osteoarthritis were included. Patients who had undergone prior parathyroidectomy were excluded. Patients were stratified by serum calcium level, HPT diagnosis, and PTH level. Arthroplasty rates were compared between groups.

RESULTS

Of 54,788 patients, 9,967 patients (18.2%) had a high serum calcium level, of whom 1,089 (10.9%) had a diagnosis of HPT. Only 76 (7.0%) patients with HPT underwent parathyroidectomy, 208 (19.1%) underwent knee/hip arthroplasty, and 14 (1.3%) underwent both. Arthroplasty was performed in 1,793 patients without evaluation and/or definitive treatment for HPT. There were higher rates of arthroplasty performed in patients with a high serum calcium level compared with those without (21.2% vs 17.4%, P < .001).

CONCLUSION

Patients with high serum calcium levels were more likely to undergo arthroplasty than those with normocalcemia. Hypercalcemia in the setting of hip or knee osteoarthritis should prompt a full evaluation for primary HPT.

Serum intact-parathyroid hormone level following total knee arthroplasty

PURPOSE

To evaluate short-term parathyroid hormone (PTH) secretion following total knee arthroplasty (TKA).

METHODS

119 Caucasian postmenopausal women aged 49 to 81 (mean, 69.8) years who underwent TKA for end-stage knee osteoarthritis were included. Serum levels of intact-PTH, calcium, phosphorus, and creatinine were evaluated pre- and post-operatively (on days -1 and 7). Creatinine clearance was also calculated.

RESULTS

In 67 of the patients, serum intact-PTH levels decreased after TKA; this sample proportion was not significant (p=0.82). In 16 of the patients, such levels elevated abnormally (above normal range). In the remaining 36 patients, such levels elevated within the normal range. Therefore, the mean serum intact- PTH level of all patients increased slightly after TKA (45.4 vs. 45.3, p=0.162). The serum intact-PTH level did not correlate to body weight (r=-0.045, p=0.624), patient age (r=-0.061, p=0.508), serum creatinine level (r=0.084, p=0.366), and clearance of creatinine (r=-0.037, p=0.692).

CONCLUSION

In most postmenopausal women, the serum intact-PTH level decreased moderately following TKA, but in some, the level was abnormally elevated. This may interfere the prosthesis incorporation process.