[3] Diagnosis is supported if pain increases when the wrist is bent inwards while a person is grabbing their thumb within a fist.

[13] Proponents of the view that de Quervain syndrome is a repetitive strain injury[14] consider postures where the thumb is held in abduction and extension to be predisposing factors.

[10] Workers who perform rapid repetitive activities involving pinching, grasping, pulling or pushing have been considered at increased risk.

[11] These movements are associated with many types of repetitive housework such as chopping vegetables, stirring and scrubbing pots, vacuuming, cleaning surfaces, drying dishes, pegging out washing, mending clothes, gardening, harvesting, and weeding.

De Quervain tendinopathy affects the tendons of these muscles as they pass from the forearm into the hand via a fibro-osseous tunnel (the first dorsal compartment).

Evaluation of histopathological specimens shows a thickening and myxoid degeneration consistent with a chronic degenerative process, as opposed to inflammation or injury.

[18] De Quervain syndrome is diagnosed clinically based on patient history and physical examination, though diagnostic imaging may be used to rule out fracture, arthritis, or other causes.

[2] To perform the test, the examiner grasps and ulnar deviates the hand when the person has their thumb held within their fist.

[1][2] If sharp pain occurs along the distal radius (top of the forearm, about an inch below the wrist), de Quervain syndrome is likely.

While a positive Finkelstein test is often considered pathognomonic for de Quervain syndrome, the maneuver can also cause some pain in those with osteoarthritis at the base of the thumb.

[2] Differential diagnoses[6] include: Most tendinoses and enthesopathies[19][20] are self-limiting and the same is likely to be true of de Quervain syndrome, although further study is needed.