<unk>  is a difficult condition to diagnose as there are no specific tests available. However, reduced capillary density has been observed microscopically during flaring; and reduced capillary perfusion is noted in the patient. Another test that can be done is to have the patient elevate their legs, and note the reversal (from red to pale) in skin color. Tests done at universities include quantitative sensory nerve testing, laser evoked potentials, sweat testing and epidermal sensory nerve fiber density test (which is an objective test for small fiber sensory neuropathy). Due to the aforementioned factors, patients may face delays in diagnosis. Once it has been established that it is not secondary<unk>  — see below — a programme of management can be put in place.Some diseases present with symptoms similar to<unk> . Complex regional pain syndrome (CRPS), for instance, presents with severe burning pain and redness except these symptoms are often unilateral (versus symmetric) and may be proximal instead of purely or primarily distal. Furthermore, attacks triggered by heat and resolved by cooling are less common with CRPS.<unk>  is sometimes caused by other disorders. A partial list of diseases known to precipitate<unk>  is below. :*Myeloproliferative disease :*Hypercholesterolemia :*Autoimmune disorder :*Small fiber peripheral neuropathy :*Fabry's disease :*Mercury poisoning :*Mushroom poisoning :*Obstructive Sleep Apnea :*Sciatica :*Some medications, such as fluoroquinolones, bromocriptine, pergolide, verapamil, and ticlopidine
Erythromelalgia
Coxalgia
Pathergy
Chromesthesia
Pressure urticaria
Heat urticaria
Onycholysis
Allodynia