| Primary deficiency |
Low dietary intake of vitamin A |
| Food source: liver beef, damascus, spinach, cabbage, milk, carrot, and butter |
| Diagnosis: food intake history, liver function, and vitamin A serum levels |
| Restrictive and monotonous diets |
Restricted intake of sources of vitamin A and consumption of the same group of food for many months |
| Eating disorders: psychiatric, cafeteria diet, and vegetarian |
| Diagnosis: food intake history. Physical signs. Blood vitamin A levels |
| Malabsorption syndrome |
Reduction in uptake and mucosa transport of digested nutrients to the blood stream |
| Diagnosis: diarrhea, steatorrhea, weight loss, anemia, hyperkeratosis, and acrodermatitis. Blood examination to check pancreas and liver function. Stool analysis (fat, parasites) |
| Bariatric surgery |
Surgery to treat obesity and associated diseases is divided into restrictive, disabsorptive, and mixed techniques and often mimics malabsorption syndrome |
| Diagnosis: surgical history, use of vitamin supplements, bowel habits. Food intake history. Physical signs. Blood levels of vitamin A. Stool analysis (fat) |
| Short bowel syndrome |
Mesenteric vascular disease typically caused by congenital obstruction, thrombosis, and other diseases requiring bowel resection |
| Diagnosis: diarrhea, fatigue. Blood levels of vitamin A. Stool analysis (fat) |
| Liver failure |
Loss of liver digestive and storage functions due to alcohol toxicity, virus infection, or other causes. Malabsorption mechanisms and signs may be present. |
| Diagnosis: blood levels of liver enzymes and vitamin A, virus serology. Stool analysis (fat) |
| Chronic pancreatitis |
Loss of pancreas exocrine function affecting digestion. Malabsorption mechanisms and signs may be present |
| Diagnosis: blood levels of pancreas enzymes and vitamin A. Stool analysis (fat) |
| Cystic fibrosis |
Inherited disease affecting chloride channels leading to exocrine gland dysfunction. Malabsorption mechanisms and signs may be present |
| Diagnosis: low weight gain in infancy, progressive malnutrition, chronic cough with hypersecretion, chronic sinusitis, biliary cirrhosis, diabetes, respiratory infections and infertility. Sodium and chloride levels in sweat |
| Salivary and deglutition diseases |
Swallowing problems due to xerostomia, tooth problems, and/or muscular deglutition dysfunction. Example: Sjogren's syndrome |
| Diagnosis: oral and dental examination and salivary flow rate |
