Surgery alters parameters of vitamin D status and other laboratory results.
Fracture liaison services often perform laboratory testing, but these results may be altered by surgery. In 40 hip arthroplasty patients, many laboratory parameters of bone health relevance were reduced by 8-22% on the first post-operative day. Laboratory results obtained in the immediate post-surgery interval do not reliably ascertain baseline status.



As secondary causes of osteoporosis are common, fracture liaison services often perform laboratory testing in the immediate post-fracture interval. We hypothesized that laboratory results obtained shortly after surgery may not accurately ascertain baseline status. If true, such alterations might confound subsequent fracture prevention efforts.



Patients undergoing elective total hip arthroplasty were studied as a surrogate for hip fracture patients. Blood and urine were obtained 2 weeks before surgery, before anesthetic induction, on post-operative day one, and 6 weeks after surgery. Serum total and free 25-hydroxyvitamin D (25(OH)D), vitamin D-binding protein (DBP), calcium, creatinine, albumin (Alb), alkaline phosphatase (ALP), plasma hemoglobin (Hgb) and urinary DBP/creatinine ratio (UDBP/Cr) were measured.



Forty volunteers (28 women; 12 men) with mean age of 65.7 [8.7] years were studied. Laboratory results were stable from 2 weeks before to the day of surgery. On the first day after surgery, total 25(OH)D, DBP, calcium, creatinine, ALP, and Alb declined 8-22% (p < 0.0001); free 25(OH)D and Hgb declined by 8 and 15% (p < 0.01), respectively; and UDBP/Cr increased 32% (p < 0.01). Using a 25(OH)D <30 ng/mL threshold, vitamin D inadequacy prevalence increased from 38% before surgery to 68% the day after (p < 0.001). All laboratory values returned to baseline at 6 weeks after surgery.



Laboratory values are reduced immediately following elective total hip arthroplasty. Testing at that time does not accurately ascertain baseline status and may lead to elevated estimates of vitamin D inadequacy, incorrect interventions, and misallocation of healthcare resources.
University of Wisconsin Osteoporosis Clinical Research Program, 2870 University Ave, Madison, WI, 53705, USA. nbinkley@wisc.edu.|Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA. nbinkley@wisc.edu.
N
http://orcid.org/0000-0002-9905-461X
N
Binkley
Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.|Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, B6/319 CSC, Madison, WI, 53792-3272, USA.
D
D
Coursin
University of Wisconsin Osteoporosis Clinical Research Program, 2870 University Ave, Madison, WI, 53705, USA.
D
D
Krueger
Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, 707 WARF Building, 610 North Walnut Street, Madison, WI, 53726, USA.
P
P
Iglar
Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA.
J
J
Heiner
Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA.
R
R
Illgen
Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA.
M
M
Squire
Creighton University Osteoporosis Research Center, 601 N. 30th Street, Suite 4820, Omaha, NE, 68131, USA.
J
J
Lappe
Creighton University Osteoporosis Research Center, 601 N. 30th Street, Suite 4820, Omaha, NE, 68131, USA.
P
P
Watson
Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, B6/319 CSC, Madison, WI, 53792-3272, USA.
K
K
Hogan
D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D005189:False Positive Reactions; D005260:Female; D006620:Hip Fractures / Q000209:etiology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D010024:Osteoporosis / Q000175:diagnosis / Q000209:etiology; D058866:Osteoporotic Fractures / Q000175:diagnosis / Q000209:etiology; D011182:Postoperative Care / Q000379:methods; D011184:Postoperative Period; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis* / Q000209:etiology*
D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
Fracture liaison service; Hip fracture; Laboratory results; Vitamin D