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Chapter 55: Aging and the Kidney

A 76-year-old Caucasian man presents with 2 months history of fatigue, nonproductive cough, hemoptysis with epistaxis, sinusitis, and nasal congestion for 5 days. Baseline serum creatinine was 1.2 mg/dL. He was evaluated by his primary care provider for symptoms of anorexia and weight loss of 5 kg (11 lb). Basic labs were collected at that time and his creatinine was found to be 3.8 mg/dL with BUN of 70 mg/dL and hemoglobin of 7.5. Chest radiograph reveals bilateral 1–2 cm nodular infiltrates’ in the upper lung field. Urinalysis showed pH of 5.5, specific gravity 1.015, +1 protein. Under the microscope, urine fields showed 0 WBCs, 10–20 RBCs/hpf with some of them dysmorphic, rare RBC casts. Kidney ultrasound was unremarkable.

On examination: BP 153/74, pulse 64, respiratory rate 24, oxygen saturation was 98% on room air, temperature 37°C. The patient is a thin, chronically ill-appearing gentleman in no apparent distress. Pertinent positives on physical examination include enlarged anterior cervical nodes with large bilateral submandibular lymphadenopathy. Crackles are heard over left anterior chest.

Which of the following tests will help establish a diagnosis?

A. Serum complements and antidouble stranded DNA antibody

B. Serum angiotensin-converting enzyme

C. Antineutrophil cytoplasmic antibodies

D. Serum immune globulin A

E. Antiglomerular basement membrane antibody

The answer is C. Patient developed acute kidney injury that is rapidly progressive with red blood cells casts along with upper airway disease is suggestive of ANCA-associated vasculitis. Serum complement can be decreased in a variety of renal pathologies including acute interstitial nephritis, lupus nephritis, and postinfectious glomerulonephritis; there is nothing in the patient’s history to support any of these entities. Increased ACE levels may be a sign of sarcoidosis as well as several other disorders. The patient’s presentation, age and race are not compatible with sarcoidosis. While crescentic IgA nephropathy can present with rapidly progressive glomerulonephritis as well as hematuria, the presence of sinusitis, hemoptysis and epistaxis points towards ANCA-associated vasculitis. Antiglomerular basement membrane antibody is present with patients with Goodpasture syndrome. The disease presents with acute kidney injury and a nephritic picture like ANCA-associated vasculitis; however, it usually occurs with pulmonary symptoms in a younger age.

A 74-year-old African–American man with past medical history of hypertension and osteoarthritis presents to the hospital with right arm abscess due to staphylocoocus aureus and is treated with antibiotic therapy. He is also on BP medication (he does not remember the name) and takes multivitamins. He improves and is discharged home. He is seen by his physician the next day with a fever—temperature 38.6°C.

His examination shows BP 118/68, pulse ...

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