Which patient with SLE should the nurse assess first?

Decreased urine output and edema in a patient with systemic lupus erythematosus (SLE) signal lupus nephritis, a life-threatening complication in which immune complex deposition damages glomeruli, leading to acute or chronic kidney injury. Renal involvement is the leading cause of major morbidity and mortality in SLE, so any sign of declining kidney function — oliguria, peripheral edema, rising creatinine — demands immediate assessment to prevent irreversible organ damage. The nurse must assess this patient first using the principle of prioritizing the most physiologically unstable client. Fatigue and joint pain are common, expected manifestations of SLE and, while distressing, are not immediately life-threatening. A photosensitive rash after sun exposure is a hallmark skin finding of SLE that is uncomfortable but does not represent an acute physiological emergency. Mild hair loss (alopecia) is another well-recognized but non-urgent feature. Among all four presentations, renal compromise carries the greatest immediate risk of deterioration, placing it at the top of the nurse's priority list.