Case Study and Clinical Highlight: A Patient With Nephrotic Syndrome and Ankylosing Spondylitis

Condensed Case Summary

A 59-year-old male patient diagnosed with ankylosing spondylitis (AS) at the age of 25, treated with sulfasalazine and intermittent nonsteroidal anti-inflammatory drugs (NSAIDs), presented to the emergency department (ED) for evaluation of anasarca and “foamy” urine that he first noted approximately 1 week prior.  Other than AS, he had a history of well-controlled hypertension.

The patient stated he had experienced generalized fatigue, easy bruising, and a tingling sensation in his hands and feet. He denied recent fever, orthostatic hypotension, chest pain, shortness of breath, abdominal pain, dysuria, or joint pain. His last evaluated AS Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score was 9.28, and his last Bath Ankylosing Spondylitis Functional Index  (BASFI) score was 8.58.

In the ED, his physical exam was notable for hypertension (158/87), sallow complexion, and generalized 2+ pitting edema of his extremities bilaterally. Chest auscultation was within normal limits. No hepatomegaly or splenomegaly was noted during abdominal palpation. No calf pain was elicited after dorsiflexion of his feet. No palpable cords or areas of induration were found in his lower extremities. Gross strength was preserved in his extremities.

Urinalysis Revealing Casts. Casts appears as cylindrical structures after formation in the tubular lumens of the kidney.

His EKG revealed sinus tachycardia, with a heart rate of 103 beats per minute. His basic metabolic panel was pertinent for a creatinine of 1.9.  His CBC revealed mild normocytic anemia and normal platelet and white blood cell counts. Coagulation profile and liver function tests were within normal limits. Urine dipstick revealed 4+ proteinuria with no noted leukocytes or glucosuria. Examination of urine sediment revealed presence of waxy casts, without the presence of red blood cells.  

Renal ultrasound preliminary results were significant for diffusing echogenicity consistent with intrarenal fibrosis. A 24-hour collection of urine was initiated and an echocardiogram was ordered. Consent was given for abdominal fat pad biopsy, which revealed green birefringence under polarized light with Congo Red staining. Immuno-histology is pending.

Further workup was significant for increased levels of serum amyloid A(SAA) and C-reactive protein (CRP). Serum immunoglobulin levels were ordered and no polyclonal hypergammaglobulinemia was noted. 

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