A 35-year-old male presents to an acute care clinic because of blood in his urine

A 35-year-old male presents to an acute care clinic because of blood in his urine. His vital signs are a temperature of 98.9°F and blood pressure of 141/89 mm Hg. Urinalysis identifies red blood cell casts and 2+ protein. His only significant past medical history is that 4 months ago, he went to the same clinic with complaints of shortness of breath accompanied by a cough that occasionally produced blood. A chest X-ray revealed infiltrates, and he was diagnosed with Mycoplasma pneumonia. He has no other significant past medical history. Of the following, what is his most likely diagnosis?

A. Mycobacterium tuberculosis infection

B. Pulmonary neoplasm

C. Goodpasture’s syndrome

D. Idiopathic pulmonary hemosiderosis

E. Organizing lobar pneumonia with septic emboli to the kidney

Given the clinical information provided, the most likely diagnosis for this patient is:

C. Goodpasture’s syndrome

The patient’s history of Mycoplasma pneumonia, followed by the current presentation of blood in urine (hematuria) along with red blood cell casts and proteinuria on urinalysis, raises suspicion for Goodpasture’s syndrome. Goodpasture’s syndrome is an autoimmune disorder that primarily affects the lungs and kidneys. It is characterized by the development of autoantibodies against the basement membranes of the alveoli in the lungs and the glomeruli in the kidneys.

The patient’s previous episode of cough with blood production (hemoptysis) and lung infiltrates, combined with the current urinary findings, suggests a connection between the lung and kidney involvement. This is a hallmark of Goodpasture’s syndrome.

Options A (Mycobacterium tuberculosis infection), B (Pulmonary neoplasm), D (Idiopathic pulmonary hemosiderosis), and E (Organizing lobar pneumonia with septic emboli to the kidney) are less likely based on the clinical information provided. None of these options explain the combination of lung and kidney involvement and the specific symptoms and findings described in the case.