Vitamin D deficiency in adult patients with primary immune thrombocytopenia (ITP) from the Vienna ITP Biobank

Introduction Primary immune thrombocytopenia (ITP) is an autoimmune disease, characterized by low platelet counts and heterogeneous bleeding phenotypes. 25-(OH) vitamin D (VD) has been reported to have immunomodulatory properties. Vitamin D deficiency (VDD) has been associated to more severe courses of ITP. In this study, we investigated VD levels in a large and well-characterized adult ITP patient cohort to analyze their association with disease duration, bleeding severity and platelet counts.

Method Levels of VD were investigated in 119 adult primary ITP patients (28 acute, 12 persistent, 79 chronic) and 20 age- and sex- matched healthy controls (HC) included in the Vienna ITP Biobank (EC 1843/2016). Recommended serum VD levels are between 75-250 nmol/L, levels below 75 nmol/L were categorized as VDD. Bleeding severity was recorded by an ITP-specific bleeding assessment tool (SMOG Score). To investigate the influence of VD levels on bleeding severity and platelet counts and selected clinical and laboratory parameters, a linear regression analysis was performed.

Results Table 1 depicts clinical and laboratory data of all ITP patients, ITP patients with VDD, normal VD, and HC. VDD patients in comparison to patients with normal VD levels had a lower rate of women (59.6% vs 95.0% vs, p= 0.002) and a higher median BMI than those with sufficient VD (26.3 kg/m2 vs 23.4 kg/m2, p= 0.025). No relevant differences in age, disease duration, bleeding severity, or platelet counts were observed between ITP patients with VDD or normal VD levels

ITP patients had lower median (IQR) VD levels than HC (49.1 (29.5-65.1) nmol/L and 64.3 (52.9-79.5) nmol/L, p< 0.01), [Fig. 1a].The rate of VDD was high in both groups, even slightly higher in ITP patients than in HC with 99/119 ITP patients (83.2%) and 14/20 HC (70.0%), p=0.162. Acute, persistent and chronic ITP cases did not differ significantly in VD levels, and HC had significantly higher VD than all three subgroups, [Fig. 1b].In ITP patients, VD levels were not associated with bleeding severity (R2= 0.002, β= 0.045, p= 0.624), platelet counts (R2= 0.004, β= 0.065, p= 0.485), age, disease duration, BMI, or Ca levels (not shown). However, a dependence of VD by sex (R2=0.045, β= 0.213, p= 0.020) and current treatment (R2=0.040, β= 0.201, p= 0.029) was observed in the total ITP cohort. Women had higher median (IQR) VD than men (52.2 (26.9-58.7) nmol/L vs 44.8 (35.1-74.3) nmol/L, p=0.043), treated patients had a tendency for lower VD ([Fig. 1c, d]).

Fig. 1 Clinical and laboratory data of all patients with primary ITP (n=119), ITP patients with vitamin D deficiency (VDD, n=99), normal vitamin D levels (n=20) and healthy controls (HC)(n=20).Notes: Values are given either as numbers and percentage or as median (25 th-75 th perecentile). SMOG, skin-mucosa-organ-gradation; 25-(OH) VD, 25-Hydroxy Vitamin D; VDD, Vitamin D deficiency; VD, 25-(OH) VD. SMOG Score was recorded using consensus-based ITP-specific bleeding assessment tool, according to the recommendations of the International Working Group (IWG) for ITP.

Conclusion In this study, VD levels were lower in ITP patients than in HCs. VD levels were independent of age, disease duration, BMI, Ca levels. No association of VDD with increased bleeding severity was found in our cohort of adult ITP patients. In line with previous data, VD levels did not correlate with platelet counts ([Fig. 2]).

Fig. 2 A. Significant difference in 25-(OH) D in ITP patients (n=119) versus healthy controls (n=20) (p=0.009) B. Significant differences in 25-(OH) D between acute ITP vs healthy controls (p=0.003), persistent ITP vs healthy controls (p=0.038) and chronic ITP vs healthy Controls (p=0.004). C. Female ITP patients show significantly lower25-(OH) D than male patients (p=0.043) D. No significant difference in 25-(OH) D between treated and untreared ITP patients. ** p<0.05; p<0.01.

Publication History

Article published online:
20 February 2023