Differential Diagnosis for Elevated Albumin-to-Creatinine Ratio (ACR) in a 73-Year-Old Woman
Single Most Likely Diagnosis
- Diabetic Nephropathy: Given the patient's history of type 2 diabetes mellitus (T2DM), even though her last HbA1c was within the normal range and she is currently managed with diet alone, diabetic nephropathy remains a likely cause for the elevated ACR. Chronic kidney damage from diabetes can lead to proteinuria, which is indicated by an elevated ACR.
Other Likely Diagnoses
- Hypothyroidism: Although the patient's levothyroxine dose was recently increased due to subclinical hypothyroidism, and this led to an improvement in serum sodium, hypothyroidism can cause renal dysfunction and proteinuria. The recent adjustment in thyroid medication might not have fully addressed the renal implications of her hypothyroid state.
- Chronic Kidney Disease (CKD) of Unknown Etiology: The patient has multiple comorbid conditions, including chronic illnesses and a history of significant medical interventions, which could contribute to CKD. The presence of anaemia, a common complication of CKD, supports this possibility.
- Medication-Induced Nephropathy: Although not specified, the patient is likely on multiple medications due to her complex medical history. Certain medications can cause nephropathy or exacerbate existing renal conditions, leading to proteinuria.
Do Not Miss Diagnoses
- Renal Amyloidosis: Given the patient's long-standing history of chronic infections (e.g., bronchiectasis, chronic sphenoidal sinusitis) and other inflammatory conditions, there is a small but critical risk of renal amyloidosis, which can present with proteinuria.
- Obstructive Uropathy: The patient's history of uterine fibroids could potentially lead to urinary tract obstruction, especially if the fibroids are large or if there are other pelvic abnormalities. Obstructive uropathy can cause renal dysfunction and proteinuria.
- Vasculitis or Systemic Lupus Erythematosus (SLE): Although less likely, given the absence of specific symptoms or history suggestive of these conditions, they are important to consider due to their potential for severe renal involvement and the fact that they can sometimes present subtly in older adults.
Rare Diagnoses
- Alport Syndrome: This genetic disorder affecting the type IV collagen in the kidneys, ears, and eyes is rare and typically presents earlier in life. However, some forms may have a later onset, and it could be considered in the differential diagnosis of proteinuria, especially if there's a family history.
- Light Chain Nephropathy: Associated with plasma cell dyscrasias, this condition can cause renal failure and proteinuria. It is less likely but should be considered, especially given the patient's age and the potential for underlying hematologic malignancies.
- Fibrillary Glomerulonephritis: A rare cause of nephrotic syndrome characterized by fibrillary deposits in the glomeruli. It is an important consideration in cases of unexplained proteinuria, although it is relatively rare.