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does anyone know why do gout normally occurs in the pheripheral joints?


cheers

1. Lower temperatures in more distal joints (may affect crystalisation of uric acid)
2. pH is lower in more distal joints --> closer to the pH that uric acid crystalises at
3. Distal joints (esp MPJ) are subject to more trauma ->crystal deposition is more common in traumatised joints.

fair enough craig, but as i can vouch for (the last few days) gout occurs in the distal jts as there is a much greater chance of same jts accidentally contacting unforgiving objects( by g.. it hurts), the creator plays games with us mortals

I have a pt who has gout and is an industrial chemist and he assured me that the change in solubility of urea decreases by about a factor of 10 with a drop of only a few degrees....I believed him
Regards Phill

I am sure the reason is that peripheral joints can be traumatized more.Alsoo you notice what TIME of year it occurs most often?Why?

1)decrease temp peripheral joints decreased solubilty
2) increased frequency traum/micro tauma. inflammatory response cascade.

Hi Mike,

gout; accumulation of monosodium urate crystals occurs inthe avuacular tissues (tendons and ligaments). the peripheral joint invlement concept is not completely true. in the upper quadrant the elbow ahs high incidence. inthe foot and ankle region the first MTPJ is common site. the PIPJs are not affected.

Low temperature: the dorsalis pedis artery is a big vessel which suples the distal foot. temp is dependent on vasular supply. hoever the low temp theory may be true in pts with PVD and vascular insufficiency compromising blood supply to the distal foot. (toes are normal;ly cold in these pts not the MTPJ- open to interpretation). literature identifies a direct correlation betweeen gout incidence and PVD and HTN. considering the tendon as the target site, there is no major difference inthe temp from the muscle spindle. the solubilityof the uric cid decreases by 2.25 mg/dL with every degree fall of temp from 36 degree. a temp of 30 degree is required to bring uric acid solubility to 4 mg/dL enoug to cause a flare.

hi Mike,

ph: ph of the tissue is directly proportional to temp. and that brings us to the pevious post on temp. influence of uriic acid solubility on ph is not documented.

possible expanation for firsst MTPJ being affected: the medial aspect of the first MTPJ - two tendons cross the medial aspect of the joint (abductor halucis and flexor digitorum brevis). increased load on the medial aspect of the first MTPJ (forgot the article) (during propulsion) increass the thickness of the articular cartuilage on that side. hence the risk factors are more on the meidal side of the FMTPJ (tendon and articular cartilage) could be the reason.

explanation for as to why uric acid leaves the circulation - will post if ur interested.

hope it helped

David

Davsur 08
Could you forward your references, especially re not finding uric acid crystals in the joint space and PIP jts not being affected.

Sally

Hi Sally,

the involvement of DPIPJs of the hand is emphasised in gout (Dalbeth et al. 2007, Journal of Rheumatology) title - gout hand study. during my search of literature ive found 2 cohorts (Roodys et al. 2007 and Grahame and Smith, 2006) where incdence of gout in different joints has been investigated. PIPJ invoovement of the foot is not reported. there are 15 case studies of gout and none on PIPJ of foot. there no article which specifically state gout does not affect PIPj of the foot. it was my conclusion from the previous studies. (could be one of the difference between rheumatoid and gout foot).

regarding the
especially re not finding uric acid crystals in the joint space

i dont see ive made that comment.

uric acid crystals in the form of monosodium urate crystals are found in the joint spaces of the affected joints.

david

I asked 2 learned Rheumatologists who said nobody knows why this is. And as we all know Rheumatologists know everything. They pointed out that no one knows why rheumatoid affects the MTPJs not the IPJs either. The list goes on. Temeperature as an expalanation does not fully make sense to me as it is so tightly regulated by the body. Also you get tophi in the ears (amongst other places) and I can't believe ear muffs are the answer!