essay 7 - carbohydrate metabolism disorders - abnormal digestion and absorption of carbohydrates. hyperglycemia and hypoglycemia

what are some problems that could cause disorders in carbohydrate metabolism

1. reduced pancreatic enzymes = pancreatic amylase is the major enzyme for carbohydrate breakdown in small intestine. damage and fibrosis (chronic pancreatitis) leads to reduced secretion of pancreatic enzymes, resulting in malabsorption

2. reduced absorption area = diseases that damage or remove the intestinal mucosa such as coeliacs or chrons disease reduce the surface area for carbohydrate absorption in the small intestine

3. accelerated passage (dumping syndrome) = after gastric surgery undigested food may entering small intestine too rapidly, causing a sudden fluid shift into the intestine leading to abdominal cramping, nausea and diarrhoea

4. hyponatremia (addison’s disease) = sodium is reacquired for glucose absorption in the small intestine, in addison’s disease, low aldosterone leads to sodium loss which can impair glucose uptake

5. disaccharide deficiency (lactose intolerance) = caused by deficiency of lactase enzyme. when undigested lactose remains in the intestinal lumen it increases the osmotic pressure (attracting water), bacterial fermentation (gas and bloating) and results in osmotic diarrhoea, abdominal discomfort and flatulence

what does the liver’s uptake and output of glucose depend on

• the liver’s uptake and output of glucose and its use by peripheral tissues depends on the physiologic balance of several hormones:

• hormones lowering blood glucose = insulin

• hormones increasing blood glucose (counter insular) = glucagon, adrenaline, growth hormone and glucocorticoids

define hyperglycaemia

• an elevated blood glucose level above normal physiological range (more than 6mmol/L).

what are some reasons for hyperglycemia to occur

1. alimentary = increased carbohydrate intake

2. increased levels of counterinsular hormones = in stress states, Cushing’s syndrom or acromegaly, hyperglycemia develops due to enhanced glucogenesis and glycogenolysis

3. decreased insulin production = seen in type 1 diabetes

4. insulin resistance = seen in diabetes type 2, insulin is present, but target tissues (muscle, liver, fat) Respond poorly → impaired glucose uptake increased hepatic glucose output

5. other = hyperthermia, hypoxia, severe pain

acute symptoms of hyperglycemia and chronic complications

• acute Symptoms = polyurea, polydipsia, polyphagia and fatigue

• chronic complications = microvascular disease and macrovascular disease

define hypoglycaemia

• decreased blood glucose level below the normal physiological range (less than 3 mmol/L)

reasons for hypoglycemia to occur

1. increased levels of insulin or hypoglycemic drugs

2. inadequate glucose production; impaired hepatic glucogenesis or glycogenolysis

3. increase glucose utilisation; exercise, sepsis or critical illness

4. Contra insular human deficiency e.g addison’s disease

symptoms of hypoglycemia and chronic complications

• symptoms = sweating, tremors, anxiety, hunger, headache, confusion, coma, seizures and irritability

• complications = the brain is highly dependent on glucose, so if there is prolonged hypoglycaemia there is a risk of brain damage