Differential Diagnosis for a 75-year-old patient with elevated laboratory values

The patient presents with several abnormal laboratory values, including elevated creatinine, azotemia, and CRP (C-reactive protein). Based on these findings, the differential diagnosis can be organized into the following categories:

• Single most likely diagnosis:
  • Chronic Kidney Disease (CKD): The elevated creatinine (0.87 mg/dl) and azotemia (53.91 mg/dl) levels suggest impaired kidney function. The patient's age and the presence of other comorbidities (not specified) increase the likelihood of CKD.
• Other Likely diagnoses:
  • Urinary Tract Infection (UTI): The elevated CRP (0.71 mg/dl) and azotemia levels could indicate an infectious process, such as a UTI, which is common in elderly patients.
  • Dehydration: The elevated creatinine and azotemia levels could also be indicative of dehydration, which is a common issue in elderly patients, especially if they have decreased fluid intake or increased fluid loss.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
  • Sepsis: Although less likely, sepsis is a life-threatening condition that can present with elevated CRP, azotemia, and impaired kidney function. It is essential to consider sepsis, especially in elderly patients with compromised immune systems.
  • Acute Kidney Injury (AKI): AKI is a potentially life-threatening condition that can cause rapid deterioration of kidney function. The patient's elevated creatinine and azotemia levels could indicate AKI, which requires prompt diagnosis and treatment.
• Rare diagnoses:
  • Multiple Myeloma: The elevated CRP and azotemia levels could be indicative of multiple myeloma, a rare plasma cell disorder that can cause kidney damage and impaired function.
  • Amyloidosis: Another rare condition that can cause kidney damage and impaired function, amyloidosis could be considered in the differential diagnosis, especially if the patient has other systemic symptoms or signs of amyloid deposition.