Vitamin D status in gastrointestinal and liver disease

Vitamin D and the vitamin D receptor in liver pathophysiology

Vitamin D through the vitamin D nuclear receptor (VDR) plays a key role in mineral ion homeostasis. The liver is central in vitamin D synthesis, however the direct involvement of the vitamin D-VDR axis on the liver remains to be evaluated. In this review, we will describe vitamin D metabolism and the mechanisms of homeostatic control. We will also address the associations between the vitamin D-VDR axis and pathological liver entities, such as non-alcoholic fatty liver disease, autoimmune liver disease, viral hepatitis and liver cancer. The link between liver diseases and the vitamin D-VDR axis will be discussed in light of evidences arising from in vitro and in vivo studies. Finally, we will consider the therapeutic potential of the vitamin D-VDR axis in liver diseases.

Vitamin D deficiency in cirrhosis relates to liver dysfunction rather than aetiology

AIM: To examine the vitamin D status in patients with alcoholic cirrhosis compared to those with primary biliary cirrhosis.

METHODS: Our retrospective case series comprised 89 patients with alcoholic cirrhosis and 34 patients with primary biliary cirrhosis who visited our outpatient clinic in 2005 and underwent a serum vitamin D status assessment.

RESULTS: Among the patients with alcoholic cirrhosis, 85% had serum vitamin D levels below 50 nmol/L and 55% had levels below 25 nmol/L, as compared to 60% and 16% of the patients with primary biliary cirrhosis, respectively (P < 0.001). In both groups, serum vitamin D levels decreased with increasing liver disease severity, as determined by the Child-Pugh score.

CONCLUSION: Vitamin D deficiency in cirrhosis relates to liver dysfunction rather than aetiology, with lower levels of vitamin D in alcoholic cirrhosis than in primary biliary cirrhosis.

Disturbances of parathyroid hormone-vitamin D axis in non-cholestatic chronic liver disease: a cross-sectional study

PURPOSE

Liver has an important role in metabolism of vitamin D. This study aimed to evaluate the patterns of vitamin D-parathyroid hormone (PTH) disturbance and correlate it in patients with non-cholestatic chronic liver disease (CLD).

METHODS

A total of 40 healthy controls and 90 consecutive patients with evidence of non-cholestatic CLD due to hepatitis C (n = 28), hepatitis B (n = 26), autoimmune hepatitis (n = 19), and cryptogenic causes (n = 17) were enrolled. Cirrhosis was evident in 51 patients. Serum concentrations of 25-hydroxy vitamin D, PTH, calcium, phosphate, and liver enzymes were measured. Child-Pugh classification was determined in cirrhotic patients.

RESULTS

Vitamin D deficiency (<50 nmol/l) was found in 46 (51.1%) patients and vitamin D insufficiency (50-80 nmol/l) in 15 (16.7%) patients. Secondary hyperparathyroidism (serum PTH > 6.8 pmol/l) was present in 6 (6.7%) patients. The prevalence of vitamin D deficiency was significantly higher in cirrhotic versus noncirrhotic patients (76.5 vs. 17.9%; P < 0.001), whereas there was no significant difference in serum calcium, phosphate, and PTH levels. Child-Pugh class B and C patients had significantly lower vitamin D level compared with class A patients (P < 0.001), whereas there was no significant difference in serum calcium, phosphate, and PTH levels. No significant correlation was seen between vitamin D and PTH, calcium or phosphate levels. Lower serum level of vitamin D was associated with coagulopathy, hyperbilirubinemia, hypoalbuminemia, anemia, and thrombocytopenia.

CONCLUSIONS

Vitamin D inadequacy and the severity of liver dysfunction move in parallel in patients with non-cholestatic CLD. Vitamin D assessment and replacement should be considered in the management of patients with non-cholestatic CLD.