A 56-year-old woman is found on health screening to have a blood pressure of 168/109 mm Hg. No other physical examination findings are noted. Urinalysis shows a pH of 7.0; specific gravity, 1.020; 1+ proteinuria; and no blood, glucose, or ketones. The ANA and ANCA test results are negative. The serum urea nitrogen level is 51 mg/dL, and the creatinine level is 4.7 mg/dL. The hemoglobin A1c concentration is within the reference range. An abdominal ultrasound scan shows bilaterally and symmetrically small kidneys with no masses. What is her most likely diagnosis?
A Amyloidosis
B Autosomal dominant polycystic kidney disease
C Chronic glomerulonephritis
D Microscopic polyangiitis
E Nodular glomerulosclerosis
The Correct Answer and Explanation is :
The most likely diagnosis for this 56-year-old woman is C. Chronic glomerulonephritis.
Explanation:
This patient presents with hypertension (168/109 mm Hg), renal dysfunction (elevated serum urea nitrogen of 51 mg/dL and creatinine of 4.7 mg/dL), proteinuria (1+ protein on urinalysis), and small kidneys seen on ultrasound, which are suggestive of chronic kidney disease (CKD). The negative ANA and negative ANCA help rule out autoimmune causes of glomerulonephritis, such as systemic lupus erythematosus (SLE) or vasculitis like microscopic polyangiitis.
The findings that point towards chronic glomerulonephritis are:
- Chronic kidney damage: The small kidneys seen on ultrasound reflect long-standing kidney damage, which can occur in chronic glomerulonephritis, where there is progressive scarring of the glomeruli leading to kidney shrinkage over time.
- Hypertension and renal dysfunction: Chronic kidney disease often presents with elevated blood pressure and deteriorating renal function (high serum creatinine and urea levels).
- Proteinuria: Although proteinuria is mild in this patient (1+), it is a common finding in chronic kidney diseases, especially glomerulonephritis.
Why the other options are less likely:
- A. Amyloidosis: This can present with renal involvement, but typically it causes more significant proteinuria and often presents with other systemic findings, such as carpal tunnel syndrome or macroglossia. The absence of these features makes amyloidosis less likely.
- B. Autosomal dominant polycystic kidney disease (ADPKD): ADPKD typically presents with bilateral large kidneys due to cyst formation, which is not seen in this patient, who has small kidneys.
- D. Microscopic polyangiitis: This condition can cause glomerulonephritis, but the patient has negative ANCA (antineutrophil cytoplasmic antibodies), which would typically be positive in microscopic polyangiitis. Additionally, the absence of pulmonary or skin symptoms also makes this diagnosis less likely.
- E. Nodular glomerulosclerosis: This is usually seen in diabetic nephropathy or chronic hypertension, but the patient’s hemoglobin A1c is within normal limits, and there is no specific history suggesting diabetes or long-standing hypertension that would point to nodular glomerulosclerosis.
Thus, chronic glomerulonephritis is the most fitting diagnosis based on the patient’s presentation.