essay 9 - protein metabolism disorders - abnormal digestion and absorption of proteins. changes in serum proteins

describe protein metabolism disorders

• impaired digestion of proteins can be due to gastric causes (Atrophic Gastritis and gastrectomy) leading to reduced pepsin and gastric acid secretion which leads to inactivation of pepsinogen, Leaving proteins largely under natured and unhydrolyzed.

• it can also be due to pancreatic reasons such as reduced pancreatic enzymes (Trypsin, chymotrypsin) in case of chronic pancreatitis, this leads to inability of cleaving large peptides into small peptides and amino acids, leading to malabsorption of amino acids.

• impaired absorption can be due to mucosal damage (celiacs, Crohn’s disease) as atrophy of the villi reduces absorptive surface and brush order enzymes, leading to malabsorption

• consequences:

— protein malnutrition

— edoema = decrease levels of serum proteins leads to accumulation of fluids in tissues

— growth and developmental issues

list The types of serum proteins

• albumin

• globulins (alpha 1 alpha 2, beta and gamma)

• fibrinogen

describe hyperproteinemia

• an increase in serum protein levels, usually due to excessive globulins. Total plasma concentration more than 80g/L

• causes:

— dehydration e.g diarrhoea, vomiting

— increase production of specific proteins e.g multiple myeloma

— chronic infections

• consequences:

— hyper viscosity of blood

— impaired microcirculation

— organ damage (renal failure in myeloma due to light chains)

describe hypoproteinemia

• a decrease in serum protein levels, especially albumin. Total plasma protein concentration less than 60g/L

• causes:

— malnutrition → insufficient dietary protein intake

— malabsorption → defective protein absorption in GI tract

— renal loss → Nephrotic syndrome → proteinuria

— liver dysfunction → cirrhosis, hepatitis→ decrease in protein synthesis

— increase catabolism → malignancy, Severe infections

• consequences:

— decrease oncotic pressure → edoema, acites, effusion

— muscle wasting, poor wound healing, immune weakness