Match each clinical presentation and laboratory finding with the most likely underlying nephrological diagnosis.
- A 58-year-old man treated with high-dose intravenous acyclovir for herpes simplex encephalitis develops an abrupt rise in serum creatinine within 48 hours. Urinalysis shows needle-shaped crystals and hematuria.Crystal-induced acute kidney injury
- A 62-year-old woman with a history of poorly controlled rheumatoid arthritis presents with nephrotic-range proteinuria. Renal biopsy reveals amorphous extracellular deposits in the mesangium that show apple-green birefringence under polarized light after Congo red staining.AA Amyloidosis
- A 71-year-old man undergoes coronary angiography. Five days later, he develops acute kidney injury, a reticular, erythematous skin rash on his lower extremities, and peripheral eosinophilia. Urinalysis is bland.Atheroembolic renal disease
- A 45-year-old woman with bipolar disorder on long-term lithium therapy presents with polyuria. Water deprivation testing results in a urine osmolality of 150 mOsm/kg, which remains unchanged following the administration of exogenous desmopressin.Nephrogenic diabetes insipidus
- A 38-year-old man with HIV on a highly active antiretroviral therapy regimen including tenofovir presents with hypokalemia, non-anion gap metabolic acidosis, hypophosphatemia, and glycosuria with a normal blood glucose level.Proximal (Type 2) renal tubular acidosis
Answer
The correct matches are: Acyclovir use with needle-shaped crystals correlates to Crystal-induced acute kidney injury. Rheumatoid arthritis with apple-green birefringence correlates to AA Amyloidosis. Post-angiography AKI with livedo reticularis correlates to Atheroembolic renal disease. Lithium use with lack of ADH response correlates to Nephrogenic diabetes insipidus. Tenofovir use with glycosuria and hypophosphatemia correlates to Proximal (Type 2) renal tubular acidosis.
Each vignette provides pathognomonic clues for a specific renal pathology. Acyclovir is notorious for precipitating in renal tubules. Chronic inflammatory conditions drive serum amyloid A overproduction leading to AA amyloidosis. Invasive vascular procedures can dislodge cholesterol crystals causing atheroembolic disease with systemic features. Lithium commonly impairs the collecting duct's response to ADH. Finally, tenofovir is a known cause of Fanconi syndrome, manifesting as a generalized proximal tubular dysfunction.
Step-by-Step Solution
Key Concept
Differentiation of complex nephrological syndromes based on specific medication toxicities, systemic disease manifestations, and pathognomonic biopsy or urinary findings.