A client with severe chronic liver disease reports difficulty seeing at night. Which vitamin deficiency is most likely responsible?

• A. Thiamine
• B. Riboflavin
• C. Vitamin A
• D. Vitamin K

Answer: (C)

Night vision depends on vitamin A for forming rhodopsin in rod cells; without enough vitamin A, the retina cannot regenerate rhodopsin efficiently, leading to difficulty seeing in the dark. In severe chronic liver disease, fat-soluble vitamins, including vitamin A, are at risk for deficiency because bile production and flow can be impaired and hepatic storage of vitamin A is reduced. Vitamin A is stored in the liver and transported in the blood by retinol-binding protein, which can be affected by liver dysfunction, making night vision problems a likely sign of vitamin A deficiency. The other vitamins listed don’t cause night blindness—thiamine deficiency affects energy metabolism and can cause neuropathy or Wernicke’s encephalopathy; riboflavin deficiency causes mucocutaneous changes; vitamin K deficiency leads to bleeding problems.