Module 2: Chemical Pathology and Immunology: Practice Questions
1. (C3) A 33-year-old woman has been drinking large amounts of water for the past week. On examination her temperature is 37 C, pulse 109/min, respiratory rate 25/min, and blood pressure 95/65 mm Hg lying down and 80/50 mm Hg standing. She has dry mucous membranes and skin tenting. Which of the following serum laboratory tests is most useful for elucidating the mechanism for her disease?
A. Albumin
B. Bicarbonate
C. Cortisol
D. Creatinine
E. Osmolality
F. Protein electrophoresis
Answer: E: Osmolality.
The findings suggest diabetes insipidus, with excessive free water excretion and thirst.
2.(C6) An 81-year-old woman has had fever with burning pain on urination for the past 4 days. On examination she has suprapubic tenderness. Laboratory studies with CBC show WBC count of 14,700/microliter with 80% segmented neutrophils, 17% lymphocytes, and 3% monocytes. Which of the following urinalysis findings is most indicative of renal involvement in this woman?
A. Bacteriuria > 100,000/mL
B. Dysmorphic red blood cells
C. Positive leukocyte esterase
D. Specific gravity of <1.010
E. White blood cell casts
Answer: E: White blood cell casts.
Only casts can come from the kidney, having formed in distal and collecting tubules. She has a urinary tract infection, and it could ascend to cause acute pyelonephritis.
3. (C7) A 68-year-old man undergoes colonoscopy. A 6 cm ulcerated, circumferential mass is found in the descending colon. Which of the following sets of laboratory findings is most indicative of hepatic involvement by this colonic process?
AST
ALT
Alk Phos.
Albumin
Bilirubin
A.
Normal
Normal
Normal
Normal
Elevated
B.
Normal
Normal
Elevated
Normal
Normal
C.
Normal
Normal
Elevated
Normal
Elevated
D.
Elevated
Elevated
Normal
Decreased
Normal
E.
Elevated
Elevated
Normal
Normal
Elevated
F.
Elevated
Elevated
Elevated
Decreased
Elevated
Answer: B.
He likely has a colonic adenocarcinoma, and one of the most common places for metastases is the liver. Hepatic masses are focal, and will obstruct a portion of the biliary tree to elevated alkaline phosphatase. However, there is enough remaining normal liver to provide synthetic function (albumin) and clearance with excretion of bilirubin. Without an inflammatory or destructive process, the hepatic AST and ALT may not be significantly elevated.
4. (C8) A 66-year-old man has had back pain for 6 months. He now has a productive cough and fever. A chest x-ray shows patchy pulmonary infiltrates. Laboratory findings include total protein 9 g/dL, albumin 4.3 g/dL, globulin 4.7 g/L, alkaline phosphatase 200 U/L, AST 50 U/L, ALT 20 U/L, and total bilirubin 1 mg/dL. Which of the following additional laboratory findings is he most likely to have?
A. Alpha-1-antitrypsin deficiency
B. Bence-Jones proteinuria
C. Blasts on the peripheral blood smear
D. Positive hepatitis B surface antigen test
E. Positive HIV test
Answer: B: Bence-Jones proteinuria.
Subtracting albumin from total protein yields 4.7 g/L of globulin, a very high amount suggesting hyperglobulinemia. Along with the bone involvement and pneumonia, multiple myeloma is most likely.
5. (C9) A 45-year-old woman has had a cough with hemoptysis for the past month. On examination she has rales in all lung fields. A chest x-ray shows reticulonodular infiltrates. Laboratory findings include serum creatinine 4 mg/dL and urea nitrogen 38 mg/dL. Which of the following autoantibody tests is most likely to be useful in diagnosis of her underlying disease?
A. Anti-cyclic citrullinated peptide
B. Anti-DNA topoisomerase I
C. Anti-double stranded DNA
D. Anti-neutrophil cytoplasmic antibody
E. Anti-ribonucleoprotein
Answer: D: Anti-neutrophil cytoplasmic antibody.
he has ANCA-associated vasculitis with pulmonary and renal involvement by necrotizing granulomatous vasculitis. Vasculitides may be accompanied by ANCAs.
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