When a patient is thyrotoxic, meaning they are having severe hyperthyroidism symptoms such as high blood pressure, high pulse rate, or anxiety, for example, the ability to make a rapid diagnosis of Graves' disease becomes particularly important.

Researchers have found that a more effective, rapid diagnosis can be made if three parameters are considered:

• Total T3/T4 ratio
• TSH
• Total Alkaline Phosphatase (T-ALP) activity

The researchers determined that findings of these three tests, results of which can be obtained within an hour in many hospital laboratories, can help diagnose Graves' disease:

• Total T3/T4 (ng/µg) ratio greater than 20 increases likelihood ratio to 2.14
• TSH less than 0.005 µU/ml increases likelihood ratio to 2.12
• Elevated T-ALP increases likelihood ratio to 4.07

When a patient had all three positive parameters, the likelihood ratio increased to 5.81.

Source: Tetsuo Yanagisawa et. al. "Rapid Differential Diagnosis of Graves' Disease and Painless Thyroiditis Using Total T3/T4 Ratio, TSH, and Total Alkaline Phosphatase Activity" Endocr J Vol. 52: 29-36, (2005)