Hereditary Fructose Intolerance
Hereditary fructose intolerance is an autosomal recessive disease caused by a lack of aldolase B, which leads to the accumulation of fructose-1-phosphate. Fructose-1-phosphate binds to free phosphate, thereby acting as a phosphate sink and depleting intracellular stores. The build-up of unmetabolized fructose leads to its presence in the urine, which presents as a reducing sugar in the urine. Despite this, urine dipstick tests are negative, as they only test for the presence of glucose. Patients are only symptomatic after eating fructose, so babies often present after eating fruit, juice, or honey. Symptoms include vomiting, hypoglycemia, jaundice, and even eventual liver cirrhosis.