|
E-Case
October 15-22, 2001
Melissa Chen R-2
A 23 year old woman tells you in clinic that her father was just diagnosed
with hemachromatosis, and she was told that she should see her doctor.
She is otherwise feeling healthy and has no complaints. PE is benign.
What workup will you do?
Hemochromatosis is the most common inherited disease in those of Nordic/Celtic
ancestry - about 10% are heterozygous for the C282Y mutation. Mutations
in this gene cause increased iron absorption, which results in buildup
of iron in tissues such as the liver, pancreas, heart, pituitary, and
thyroid.
- Genetic testing for C282Y and H63D mutations:
Patients develop hemochromatosis if they are homozygous for the C282Y
mutation, or have a C282Y mutation on one chromosome and an H63D mutation
on another (the compound heterozygous state).
- Baseline LFTs, CBC, and iron studies
(Iron, TIBC) and fasting ferritin.
- Criteria for being able to nix the liver biopsy:
- Homozygous for C282Y, ferritin <1000, normal AST, and no hepatomegaly.
When do you decide to initiate therapeutic phlebotomy?
- When ferritin >200 in nonpregnant women; >300 in men; >500
in pregnant women.
- Initially, schedule phlebotomy weekly. Don't allow Hct to fall by
more than 20% of the prior level. Check ferritin every 10-20 phlebotomies.
Goal: ferritin <50.
What are the clinical manifestations?
Iron accumulates at a rate of about 1gram/year. End organ damage won't
happen until > 20 grams accumulates, so patients usually won't get
symptoms until they're over 40 years old. If therapeutic phlebotomy is
initiated before cirrhosis or diabetes develops, survival returns to normal.
Many symptoms can be prevented or improved with therapeutic phlebotomy.
- Liver disease: hepatomegaly,
elevated LFTs, cirrhosis.
Hepatocellular carcinoma risk greatly increased in those who have developed
cirrhosis.
- Diabetes from pancreatic iron
deposition. Patients on insulin may require less after iron removal.
- Arthropathy: Typically 2nd
and 3rd MCP joint, wrist. Often looks like CPPD. Unaffected
by extent of iron accumulation or iron removal.
- Dilated cardiomyopathy. Most
common EKG abnormality is ventricular ectopy.
- Decreased libido / secondary hypogonadism
from iron deposition in pituitary cells
- Osteoporosis (especially if hypogonadal)
- Hypothyroidism from iron deposition
in thyroid.
- Susceptibility to certain infections:
Hemochromatosis patients shouldn't eat uncooked seafood - they're particularly
susceptible to listeria, yersinia, and vibrio infections.
When would you screen a person without a family
history?
- Increased LFTs
- Decreased libido at a younger age than you might expect
- Characteristic arthropathy (2nd and 3rd MCPs).
When screening, note that getting a fasting level of the ferritin eliminates
80% of false positive results.
References:
Edwards, Corwin and James Kushner. "Current Concepts: Screening for
Hemochromatosis." NEJM 328 (22), 3 June
1993: 1616-1620.
Powell, Lawrie and Thomas Yapp. "Hemochromatosis." Clinics
in Liver Disease 4(1) Feb 2000: 211-228. (Next to UpToDate, this
was the most helpful source for general info.)
UpToDate.
|