Introduction
It is known that the bone fusion rate in spinal fixation surgery is inferior in cases with decreased serum vitamin D concentration (25-hydroxyvitamin D;25OHD) and understanding the prevalence and characteristics of this condition is crucial. However, the sufficiency rate of 25OHD has not been thoroughly evaluated, and there are few detailed reports on this matter. To evaluate the sufficiency status of 25OHD and elucidate its relationship with bone metabolism markers and bone density in patients undergoing spinal surgery at our hospital.
Methods
We targeted 830 cases of patients aged 60 and above who underwent elective spinal surgery at our hospital from January 2017 to August 2023 (454 males, 376 females). Patients who underwent measurements of 25OHD, bone metabolism markers (tartrate-resistant acid phosphatase 5b; TRACP5b, Procollagen I N-Terminal Propeptide; P1NP), intact parathyroid hormone (PTH), and bone density (lumbar spine %YAM value) upon admission were included in the study. The sufficiency of 25OHD and its relationship with each parameter were investigated. Blood 25OHD levels were classified as sufficient (30 ng/ml or higher), insufficient (20 ng/ml or higher, less than 30 ng/ml), and deficient (less than 20 ng/ml). The frequency of high intact PTH (65 pg/ml or higher) and %YAM (Young Adult Mean) value less than 80% were examined in each group.
Results
There were 20 cases of sufficient blood 25OHD with an average age of 75.3 years (14 males, 6 females). Insufficient cases numbered 177 with an average age of 73.3 years (127 males, 50 females). Deficient cases were 633 with an average age of 74.1 years (313 males, 320 females). The frequency of high intact PTH for sufficiency/insufficiency/deficiency was 10%/21%/27%, and the frequency of %YAM value less than 80% was 5%/12%/18% (p=0.08). A mild negative correlation was observed between 25OHD and bone metabolism markers such as TRACP5b (r=-0.11 p=0.0018) and P1NP (r=-0.01, p=0.0046).
Discussions
In this study, 98% of patients were revealed to have insufficient levels of 25OHD, suggesting a severe deficiency problem of 25OHD in elderly patients. Although 25OHD is considered insufficient in around 80% of the general population, it was revealed that cases with elderly spinal disorders have an even higher probability of 25OHD insufficiency. Reflecting the low values of 25OHD, intact PTH showed an increasing trend, and the rate of bone loss also showed an increasing trend. The association between low 25OHD levels and poor postoperative outcomes in spinal surgery has been documented by some researchers. Therefore, spine surgeons need to be aware of potential bone metabolism abnormalities and approach preoperative medication, surgical treatment, and perioperative management with caution.