A 60-year-old man comes to the urgent care center after being awakened by severe pain in his right great toe, which is suddenly swollen and very tender to the touch. He has also had occasional headaches and "unbearable" pruritus after a hot bath over the past several weeks. The patient does not use alcohol, tobacco, or illicit drugs. His temperature is 36.8 C (98.3 F), blood pressure is 140/90 mm Hg, and pulse is 90/min. Cardiopulmonary examination is normal. The abdomen is soft and nontender, and there is no appreciable ascites. The liver span is 10 cm at the mid-clavicular line, and the spleen is palpable 2 cm below the costal margin on full inspiration. His right great toe is swollen and erythematous, with severe pain on any movement. Aspiration of the affected metatarsophalangeal joint shows negatively birefringent crystals and many leukocytes but no organisms. Which of the following is most likely responsible for this patient's symptoms?

Question

A 60-year-old man comes to the urgent care center after being awakened by severe pain in his right great toe, which is suddenly swollen and very tender to the touch.  He has also had occasional headaches and "unbearable" pruritus after a hot bath over the past several weeks.  The patient does not use alcohol, tobacco, or illicit drugs.  His temperature is 36.8 C (98.3 F), blood pressure is 140/90 mm Hg, and pulse is 90/min.  Cardiopulmonary examination is normal.  The abdomen is soft and nontender, and there is no appreciable ascites.  The liver span is 10 cm at the mid-clavicular line, and the spleen is palpable 2 cm below the costal margin on full inspiration.  His right great toe is swollen and erythematous, with severe pain on any movement.  Aspiration of the affected metatarsophalangeal joint shows negatively birefringent crystals and many leukocytes but no organisms.  Which of the following is most likely responsible for this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d50b_cce1_bc81_2948f87ceee2_MD0003_00 This patient has podagra from an acute attack of gout. Gout occurs as a result of overproduction or underexcretion of uric acid. Overproduction of uric acid is typically related to consumption of a high-urate diet, but any condition that increases catabolism and turnover of purines can raise uric acid levels and trigger a gout attack. Common causes include hematologic malignancies, tumor lysis syndrome, and psoriasis. Myeloproliferative disorders are common secondary causes of gout. This patient has several clinical features suggesting polycythemia vera (PV), including pruritus triggered by hot baths (aquagenic pruritus), headaches, and hepatosplenomegaly. PV is characterized by increased cell turnover due to clonal hyperproliferation in all 3 primary bone marrow lineages (ie, red cells, white cells, platelets). Up to 40% of patients with PV have gout. Allopurinol inhibits uric acid formation and is used to prevent gout attacks in patients with hyperuricemia due to PV. (Choice A) Chronic kidney disease (CKD) can cause gout attacks due to decreased renal excretion of uric acid. CKD with significant uremia can also cause pruritus, but splenomegaly is not seen in CKD. (Choices B and C) Hyperparathyroidism causes elevated serum calcium concentrations, leading to chondrocalcinosis and calcium pyrophosphate dihydrate deposition disease (pseudogout). Hemochromatosis also causes pseudogout, as well as chronic arthritis resembling osteoarthritis. However, pseudogout usually affects the larger joints (eg, knee), and the crystals in pseudogout are positively birefringent. (Choice D) Genetic deficiency of hypoxanthine-guanine phosphoribosyl transferase (Lesch-Nyhan syndrome) is characterized by self-injurious behaviors and neurologic disability. It is associated with overproduction of uric acid but is usually diagnosed in childhood. (Choice F) Pernicious anemia is associated with macrocytic anemia and neurologic abnormalities, but not with inflammatory arthritis. (Choice G) Portal hypertension can cause splenomegaly, as well as severe pruritus due to increased serum concentrations of bilirubin. However, portal hypertension is not associated with gout. Educational objective: Gout is a common complication of myeloproliferative disorders due to excessive turnover of purines and the resulting increase in uric acid production.

A 60-Year-Old Man Comes to the Urgent Care Center After