Which symptom is specifically linked to kidney involvement in SLE?

Proteinuria is specifically linked to kidney involvement in systemic lupus erythematosus (SLE). In SLE, the autoimmune process can lead to inflammation of the kidneys, known as lupus nephritis. This condition can manifest with various symptoms related to renal dysfunction, including proteinuria, which is the presence of excess protein in the urine. Proteinuria occurs when the glomeruli, the filtering units of the kidneys, are damaged and allow proteins that would normally be retained in the bloodstream to escape into the urine.

While the other symptoms mentioned can be related to SLE, they do not specifically indicate kidney involvement. The butterfly-shaped rash is a classic cutaneous manifestation of lupus but does not reflect renal status. Fever can occur in various inflammatory conditions, including SLE, and hair loss is often due to other factors related to the autoimmune nature of the disease rather than direct kidney damage. Understanding proteinuria as a marker of kidney involvement in SLE is crucial for monitoring disease activity and managing complications effectively.