Differential Diagnosis
The patient's laboratory results indicate several abnormalities, including elevated BUN and creatinine, low calcium and albumin, and high proBNP. Based on these findings, the following differential diagnoses are considered:
- Single Most Likely Diagnosis + Chronic Kidney Disease (CKD): The patient's elevated creatinine (1.57 mg/dL) and BUN (42 mg/dL) levels, along with a low eGFR (42 mL/min/1.73 m^2), suggest impaired kidney function. The low albumin and calcium levels also support this diagnosis, as CKD can lead to proteinuria and disturbances in mineral metabolism.
- Other Likely Diagnoses + Congestive Heart Failure (CHF): The high proBNP level (2281 pg/mL) is a strong indicator of CHF, which can also contribute to the patient's elevated BUN and creatinine levels due to decreased renal perfusion. + Dehydration: Although the patient is not on diuretics, dehydration could still be a contributing factor to the elevated BUN and creatinine levels. However, the absence of other typical laboratory findings, such as hypernatremia or elevated osmolality, makes this diagnosis less likely.
- Do Not Miss Diagnoses + Acute Kidney Injury (AKI): While the patient's eGFR is low, it is essential to rule out AKI, which can be caused by various factors, including medication, infection, or obstruction. AKI can have a rapid onset and may not be immediately apparent on laboratory results. + Hyperkalemia-Inducing Conditions: The patient's potassium level is at the upper limit of normal (5.2 mEq/L). Conditions such as adrenal insufficiency, type 4 renal tubular acidosis, or certain medications can cause hyperkalemia, which can be life-threatening if not addressed promptly.
- Rare Diagnoses + Multiple Myeloma: The low albumin and calcium levels, along with a relatively normal globulin level, could suggest multiple myeloma. However, this diagnosis is less likely without other supporting laboratory or clinical findings, such as anemia, bone pain, or elevated monoclonal protein levels. + Nephrotic Syndrome: Although the patient's albumin level is low, the absence of significant proteinuria or edema makes nephrotic syndrome a less likely diagnosis. However, it is essential to consider this possibility, especially if the patient has a history of kidney disease or other underlying conditions.