In contrast to rheumatoid arthritis, in which the joints are the primary target and serositis of the lung and pericardium are uncommon, diverse organ inflammation is the rule in lupus. The lungs, heart, blood, joints, skin, kidneys, liver, eyes and central nervous system of patients may all be targeted simultaneously in a critically ill patient, or symptoms and laboratory abnormalities may unfold over decades.
But what is lupus? As a classic autoimmune disease, systemic lupus erythematosus (SLE) is a case of mistaken identity writ large. The immune system in lupus patients is in chronic overdrive, effectively performing its primary job—protecting the body from infection, while cross-reacting against normal body tissues and proteins. Ninety-nine percent of SLE patients develop anti-nuclear antibodies. Many patients have additional antibodies to proteins within the nucleus: anti-DSDNA, anti-RNP, anti-Sm, anti-histone antibodies. The list is long and growing.1
The immune system may turn against components of blood. The resultant low white blood counts predispose patients to infection, the low platelets to bleeding gums or recurrent nose bleeds. Antibodies directed to the outer membrane of red blood cells may trigger life-threatening hemolytic anemia, giving rise to pale, ghost-like victims.
The exact sequence of events leading to lupus is unclear, but like so many immunologic disorders, the disease has both a genetic predisposition and suspect environmental and infectious triggers. This much is clear. Lupus is primarily a disease of women in the child-bearing years. For every 10 cases of lupus, nine are women.2
In medical school, I was taught that lupus & syphilis were the Great Imposters, meaning their signs & symptoms mimic a host of more common disorders. On medical rounds, it was always a safe bet to include lupus in the broad differential diagnosis of any perplexing case.
Back to Our Patient
The next day, Amanda’s kidneys hovered between catastrophic failure and reversible injury. Her urine output slowed to a trickle. A nephrologist consulted and performed a kidney biopsy. I recommended two more days of high-dose Solu-Medrol, and in my notes indicated she would require a long-term immunosuppressive drug, depending on the results of the kidney biopsy.
Amanda’s urine output increased ever so slightly—the precious golden fluid draining through her Foley catheter into the collection bag at the bedside.
A hematologist consulted on her autoimmune hemolytic anemia. A cardiologist weighed in on the pericarditis. An infectious disease specialist suggested that because of Amanda’s high fevers and critical illness, antibiotics should be continued until infection could be excluded.