A patient has symptoms suspicious of deep vein thrombosis. Which lab test would be helpful to see if higher-than-normal amounts of protein fragments secondary to fibrinolysis are present in the blood?

Choice A reason: CPTT (likely a typo for aPTT, activated partial thromboplastin time) measures clotting time in the intrinsic pathway, used to monitor heparin therapy. It does not detect protein fragments from fibrinolysis. In DVT, aPTT is normal unless anticoagulation is involved, making it unhelpful for detecting fibrin degradation products.

Choice B reason: INR (international normalized ratio) assesses the extrinsic clotting pathway, primarily for warfarin monitoring. It does not measure fibrin degradation products like D-dimer. In DVT, INR is typically normal unless the patient is on anticoagulants, so it is not useful for confirming fibrinolysis or diagnosing DVT.

Choice C reason: Impedance plethysmography is a non-invasive test measuring blood flow changes in veins, used to detect DVT by identifying obstructions. It does not measure protein fragments or fibrinolysis products. It assesses physical blood flow, not biochemical markers, making it irrelevant for detecting fibrin degradation in DVT.

Choice D reason: D-dimer is a specific test for fibrin degradation products, elevated in DVT due to fibrinolysis of clots. A high D-dimer indicates active clot breakdown, supporting DVT diagnosis. It is sensitive but not specific, requiring imaging confirmation, but it directly addresses the question of detecting protein fragments from fibrinolysis.

Choice A reason: Decreased appetite is not typical in Graves’ disease, a form of hyperthyroidism. Increased metabolism from elevated thyroid hormones increases appetite, yet weight loss occurs due to catabolism. Decreased appetite may occur in hypothyroidism or other conditions, not hyperthyroidism, making this an incorrect expected finding.

Choice B reason: Muscle enlargement is not associated with Graves’ disease. Hyperthyroidism causes muscle wasting and weakness due to increased catabolism from elevated thyroid hormones. Muscle enlargement occurs in conditions like myopathies or anabolic states, not hyperthyroidism, where protein breakdown predominates, leading to reduced muscle mass.

Choice C reason: Weight loss is a hallmark of Graves’ disease, as excess thyroid hormones increase metabolic rate, accelerating calorie expenditure. Despite increased appetite, patients lose weight due to enhanced catabolism of fat and muscle. This is a classic symptom, reflecting the hypermetabolic state driven by hyperthyroidism.

Choice D reason: Fine tremor is a common finding in Graves’ disease, caused by excess thyroid hormones increasing sympathetic nervous system activity. This leads to beta-adrenergic stimulation, causing fine, resting tremors, particularly in the hands. It’s a key neurological symptom, reflecting the hyperthyroid state’s impact on motor control.

Choice E reason: Goiter, an enlarged thyroid gland, is a classic feature of Graves’ disease. Autoimmune stimulation by thyroid-stimulating antibodies causes thyroid hyperplasia, leading to a visible or palpable goiter. This enlargement is a hallmark of Graves’ disease, driven by increased thyroid hormone production, and is a key physical finding expected during assessment of this hyperthyroid condition.