Damjanov Chapter 3 Flashcards
Hereditary hemochromatosis is a common ____ disorder marked by ____ storage caused by abnormal absorption of what where? What are many of the cases due to?
Autosomal recessive; iron; iron in the intestines;
mutations of the HFE gene
HFE gene is linked to what locus on which chromosome? What is the mutation?
HLA-A locus on short arm of chromosome 6;
cysteine-to-tyrosine substitution at aa 282
Activity of DMT-1 and ferroportin is normally suppressed by what? In hereditary hemochromatosis, levels of this are high or low?
Hepcidin; low
What primes transferrin and HFE gene product for iron absorption via enterocytes?
Transferrin sensor cells
Excess iron can (3):
- excreted in the urine
- aggregate into hemosiderin granules
- formation of free radicals (inactivate enzymes involved in oxidative respiration, protein syntehsis, transmembrane transport; fibrosis; carcinogenesis because of potential DNA mutations made)
In the liver, iron accumulates in what three things? Deposits of iron pigment lead to ____, gradually progressing to frank _____. Clinically what are the changes?
Kupffer cells, hepatocytes, bile duct cells;
fibrosis, cirrhosis;
hepatomegaly, portal hypertension with splenomegaly, esophageal varices (HEP)
For HH, what color does the skin turn? What are two reasons why?
Brown;
accumulation of hemosiderin in macrophages and accumulation of melanin in epidermis
Endocrine gland consequences of HH? Where else can HH affect?
Diabetes (accumulation of hemosiderin in pancreas), thyroid, gonads, also testicular atrophy and reduced testosterone;
Joints: calcification of synovium and deposits of hemosiderin causing joint injury (2nd, 3rd MCP joints in particular); iron in myocardium leading to cardiomyopathy, heart dilatation, conduction problems
In HH, what happens to total plasma iron, transferrin sat, serum ferritin, urinary iron excretion?
They all go up
Tests for HH are performed as a ______ to avoid what? Deposits of ____ in the liver can be estimated subjectively via what? What provides the final diagnosis of HH?
battery; false positives and negatives;
iron; livery biopsy stained with Prussian blue reacting with HEMOSIDERIN;
Genetic testing
Hyperuricemia is defined empirically as
an elevation of uric acid conc in blood over 7 mg/dL
T/F: if you have hyperuricemia, you have a high prob of developing gout?
False: 90% of persons with hyperuricemia won’t develop gout
Although breakdown of ____ occurs in all tissues, ____ is produced only in organs, like the ____ and _____, that contain xanthine oxidoreductase
nucleic acids; uric acid; liver and intestines;
Uric acid is derived how? How is it eliminated?
- 2/3 derived from purine degradation; remaining third comes from diet
- 2/3 of uric acid eliminated from blood in urine, and remaining 1/3 through intestines
Solubility of ____ decreases at low temp, accounting for deposition of ____ in what tissue?
monosodium urate; urate crystals; joint tissue of big toe
List ways that uric acid is overproduced? Underexcreted?
- Primary: think Lesch-Nyhan
- Secondary: tumor lysis syndrome after chemo (release of purines); leukemia, lymphoma, chronic hemolytic anemia can cause hyperuricemia);
- excrete <700 mg of uric acid/day, like chronic renal disease
- Drugs (e.g. thiazides, aka diuretics); levodopa and cytclosporine
- Toxins: e.g. lead, affecting uric acid excretion in proximal tubules
- Metabolic disturbances: lactic acidosis, hyperparathyroidism, hypothyroid