**Question:** All of the following are included in Jones major criteria except:

A. Systemic involvement (rheumatic heart disease, valvular heart disease, or right-sided heart failure)
B. Proteinuria
C. Positive antinuclear antibody (ANA) test
D. Serum creatinine level

**Core Concept:**

Jones Criteria are a set of diagnostic criteria used to identify patients with systemic lupus erythematosus (SLE) and antiphospholipid antibody syndrome (APS). These criteria include both clinical and laboratory findings, which help in making a definitive diagnosis. Jones major criteria include systemic involvement, proteinuria, positive antinuclear antibody (ANA) test, and elevated serum creatinine level.

**Why the Correct Answer is Right:**

Option D, serum creatinine level, is not included in Jones major criteria because it is a marker of kidney function, not a direct indicator of the presence of lupus or antiphospholipid antibodies. While elevated creatinine levels can be a consequence of lupus-related kidney damage, they are not considered as a major criterion.

**Why Each Wrong Option is Incorrect:**

Option A, serum creatinine level, is incorrect for the same reason as the correct answer: it assesses kidney function but does not directly reflect the presence of lupus or antiphospholipid antibodies.

Option B, proteinuria, is considered a major criterion in Jones criteria as it is a hallmark of lupus nephritis, a common complication of SLE affecting the kidneys. Proteinuria indicates kidney damage and is indicative of lupus activity.

Option C, positive antinuclear antibody (ANA) test, is considered a major criterion as it is a specific marker for lupus. The presence of ANA in the blood indicates that the patient has an autoimmune disease, making ANA testing an important tool in diagnosing SLE.

**Clinical Pearl:**

In clinical practice, understanding the Jones criteria helps in diagnosing systemic lupus erythematosus and antiphospholipid antibody syndrome in patients with relevant symptoms and signs. The criteria include both clinical (major criteria) and laboratory findings (minor criteria) that contribute to the overall diagnosis.