Could PTH/Ca Ratio Serve as a New Marker for Evaluating Bone Metabolism in Hemophilia Patients?

<b>Background/Objectives:</b> Low bone mineral density (BMD) is common in hemophilia patients. Identifying high-risk patients for low BMD early is essential to prevent complications and reduce morbidity. The parathyroid hormone (PTH)/calcium (Ca) ratio is a cost-effective marker for predicting BMD, highlighting the need for routine screening and early intervention in this population. Hemophilia is a hereditary bleeding disorder caused by deficiencies in clotting factors VIII (hemophilia A) and IX (hemophilia B). Patients with hemophilia are at risk of low bone mineral density (BMD). This study aimed to evaluate the prevalence of low BMD, associated risk factors, and raise awareness regarding its significance in hemophilia patients. <b>Methods:</b> We retrospectively assessed bone metabolism in 62 hemophilia patients followed at our center. BMD was evaluated using dual-energy X-ray absorptiometry (DEXA). Additionally, serum levels of 25-OH-D3, alkaline phosphatase, PTH, Ca, phosphor, and creatinine were measured. The PTH/Ca, PTH/25-OH-D3, and Ca×25-OH-D3/PTH ratios were calculated. <b>Results:</b> The median age of the 62 patients with hemophilia included in the study (hemophilia A: 87.1%, hemophilia B: 12.9%) was 37 years (range: 21-66), and all were male. Of these patients, 67.7% (<i>n</i> = 42) had severe, 21% (<i>n</i> = 13) had moderate, and 11.3% (<i>n</i> = 7) had mild hemophilia. A total of 85.5% of patients were on factor prophylaxis, and 75.4% had a target joint. In laboratory analysis, the median 25-OH-D3 level was 13.4 µg/L and 75% patients had 25-OH-D3 deficiency. According to DEXA results, 62.9% had lower than normal BMD. When we divided the patients into normal and low BMD groups according to DEXA results, weight (<i>p</i> = 0.006), height (<i>p</i> = 0.024), factor levels (<i>p</i> = 0.004), PTH (<i>p</i> = 0.010), AST (<i>p</i> = 0.029), and PTH/Ca (<i>p</i> = 0.011) levels were statistically significantly different between the groups. The severity of the disease and the rate of receiving prophylaxis were higher in the group with low BMD (<i>p</i> = 0.015, <i>p</i> = 0.006, respectively). In multivariate analysis, PTH/Ca ratio and weight were found to be independent risk factors for BMD. A linear relationship was found between PTH/Ca ratio and BMD. The optimal cut-off value for PTH/Ca was 6.57, with a selectivity of 65% and specificity of 82%. When we divided the patients into groups according to the cut-off value of 6.57, we found that the probability of low BMD increased approximately 7-fold in the group with PTH/Ca > 6.57 (OR 7.045, 95% CI 1.485-33.42, <i>p</i> = 0.014). There was an inverse association between patient weight and low BMD (<i>p</i> = 0.043). <b>Conclusions:</b> Low BMD is a critical public health concern frequently observed in patients with hemophilia. The study highlights a high rate of low BMD and 25-OH-D3 deficiency in hemophilia patients, with the PTH/Ca ratio shown to be useful in predicting BMD. The PTH/Ca ratio is suggested as an accessible, cost-effective, and practical test for evaluating BMD in hemophilia patients.