R. W. Randle1, C. J. Balentine1, E. Wendt1, D. F. Schneider1, H. Chen2, R. S. Sippel1 1University Of Wisconsin,Department Of Surgery,Madison, WI, USA 2University Of Alabama,Department Of Surgery,Birmingham, Alabama, USA
Introduction:
Vitamin D deficiency is common in patients presenting with hyperparathyroidism (HPT), but the importance of replacement prior to surgery is controversial. We aimed to evaluate the impact of low vitamin D on the extent of resection and post-operative hypocalcemia for patients undergoing parathyroidectomy for primary HPT.
Methods:
We identified patients with primary HPT undergoing parathyroid surgery between 2000 and 2015 using a prospectively maintained database. Patients with normal (30ng/mL or greater) vitamin D (25-OH) levels were compared to those with levels less than 30ng/mL.
Results:
The study included 1015 (54%) patients with normal vitamin D and 872 (46%) patients with low vitamin D undergoing parathyroidectomy for primary HPT. Lower vitamin D was associated with higher preoperative parathyroid hormone (PTH) compared to normal vitamin D (median 90 vs 77pg/mL, p<.001). Calcium (median 10.5 vs 10.4mg/dL, p<.001) was also higher while phosphate (median 2.8 vs 2.9mg/dL, p<.001) was lower in patients with low vitamin D, indicating more severe disease. Despite higher preoperative and baseline PTH levels in the low vitamin D group, 10 and 15 minute post-excision PTH was similar (Figure) resulting in a greater overall drop in PTH (median drop 78 vs 72%, p<.001) and similar post-operative calcium (median 9.3 vs 9.3mg/dL, p=.13) compared with the normal vitamin D group. A subgroup analysis in patients with severely low (≤10ng/mL) vitamin D (n=67) also revealed higher preoperative PTH, similar post-excision PTH, greater drop in PTH (median drop 81 vs 72%, p<.001), and similar post-operative calcium (median 9.3 vs 9.3, p=.39) compared to those with normal vitamin D. To achieve similar cure rates, patients with low vitamin D were less likely to require 4-gland exploration (19 vs 23%, p=.009), conversion from a focused approach to 4-gland exploration (11 vs 15%, p=.01), removal of more than 1 gland (20 vs 30%, p<.001), and subtotal parathyroidectomy (8 vs 12%, p=.003) than patients with normal vitamin D. Despite undergoing a more focused operation, patients with low vitamin D had similar rates of persistent (1.5 vs 2.0%, p=.43) and recurrent (1.7 vs 2.6%, p=.21) HPT. Also, at the time of parathyroidectomy both groups had equally low rates of both transient (2.3 vs 2.3%, p=.97) and permanent (0.2 vs 0.4%, p=.52) hypocalcemia.
Conclusion:
Restoring vitamin D in deficient patients should not delay the appropriate surgical treatment of primary HPT. Even though low vitamin D may be a marker for more severe primary HPT, deficient patients are more likely to be cured with the excision of a single adenoma and no more likely to suffer persistence, recurrence, or hypocalcemia than patients with normal vitamin D.
