Examkin

Question

Difficulty: MediumOrdering Laboratory Tests

A 54-year-old man comes to the primary care clinic complaining of progressive fatigue, joint pain in his hands, and erectile dysfunction over the past 6 months. His past medical history is significant for type 2 diabetes mellitus diagnosed 8 months ago, which has been difficult to control despite adherence to metformin therapy. He does not use tobacco, alcohol, or illicit drugs. His family history is notable for a father who died of liver cirrhosis of unknown etiology. Vital signs are within normal limits. Physical examination reveals hepatomegaly and a distinct grayish-bronze hyperpigmentation of the skin, most prominent on his forearms and face. Joint examination shows tenderness and mild bony enlargement of the second and third metacarpophalangeal joints bilaterally. Genitourinary examination reveals bilateral testicular atrophy. Which of the following is the most appropriate next step in laboratory evaluation?

  1. Serum transferrin saturation and ferritin levelsAnswer
  2. B
    HFE gene mutation analysis
  3. C
    Morning serum total testosterone and luteinizing hormone
  4. D
    Hepatitis B surface antigen and hepatitis C antibody
  5. E
    Rheumatoid factor and anti-cyclic citrullinated peptide antibodies

Answer

The most appropriate next step is to order serum transferrin saturation and ferritin levels.
The patient presents with a classic constellation of symptoms for hereditary hemochromatosis, including new-onset diabetes mellitus, hepatomegaly, skin hyperpigmentation (often referred to as 'bronze diabetes'), arthropathy characteristically affecting the second and third metacarpophalangeal joints, and secondary hypogonadism (manifesting as erectile dysfunction and testicular atrophy). Hereditary hemochromatosis is characterized by excessive intestinal iron absorption leading to iron deposition and fibrosis in target organs such as the liver, pancreas, anterior pituitary, and joints. The most appropriate initial step in laboratory evaluation is screening for biochemical iron overload by measuring serum transferrin saturation and serum ferritin levels. A transferrin saturation greater than 45% is highly sensitive and warrants subsequent confirmatory testing.

Step-by-Step Solution

1
Analyze the patient's comprehensive clinical presentation.
The combination of new-onset diabetes mellitus, hepatomegaly, bronze skin hyperpigmentation, second and third metacarpophalangeal joint arthropathy, and secondary hypogonadism points to a systemic metabolic disorder.
Identifying the underlying unifying syndrome prevents premature closure on individual, isolated symptoms.
2
Identify the most likely diagnosis based on the clinical syndrome and family history.
The clinical picture and a family history of unexplained liver cirrhosis strongly suggest hereditary hemochromatosis.
Hereditary hemochromatosis typically becomes symptomatic in men in their 40s or 50s as iron progressively accumulates in target organs over decades.
3
Determine the most appropriate initial laboratory diagnostic test for the suspected condition.
The initial evaluation requires non-invasive screening for iron overload using serum transferrin saturation and serum ferritin levels.
Highly sensitive, low-cost screening tests must logically precede expensive or invasive confirmatory tests in the diagnostic sequence.

Key Concept

Hereditary hemochromatosis presents systemically with hepatomegaly, skin hyperpigmentation, diabetes mellitus, specific arthropathy, and hypogonadism; the initial diagnostic step is screening with serum iron studies prior to genetic confirmation.
Rate this question

Topics

Ordering Laboratory Tests

More questions from this topic