t-rex gout

[Valued Acer Customer <clayke@pacbell.net>]

Dear list:
I am a physician who is a long- time reader but first-time
contributer.  Although I possess no knowledge of non-huiman metabolism
and illnesses, I do know something about gout in our own species which
may be applicable to dinosaurs.  Gout is caused by a high uric acid
level which is a product of purine degredation, produced chiefly by the
liver and small intestine.  At high concentrations, uric acid in the
plasma can become supersaturated and can precipitate as urate crystal 
in the joints leading to an acute gouty arthritis.   Up to 13%
of adults have elevated uric acid levels, whereas only 2% of them ever
develop gout.  The higher the uric acid level the more likely gout
will develop.
     High uric acid levels can be
caused by over-production or under excretion.  There are a number
of illnesses associated with over-production, the most common being idiopathic
(unknown).  In dinosaurs I think some potentially relevant uric acid
elevaters would be: exercise, rhabdomyolysis (severe muscle trauma leading
to degredation of skeletal muscle ATP), obesity (quite unlikely), and a
purine-rich diet.  Such foods in humans include organ meats (liver,
kidney, sweatbreads), and anchovies.  Underexcretion of uric acid
is a more common cause of gout and causes include a number of illnesses
including the potentially important-for-dinosaurs: starvation.  Again,
the majority of cases have an idiopathic cause.  Reproductive hormones
seem to protect females; their uric acid levels begin to rise only after
menopause.
     Most first attacks of gouty
arthritis follow 20-40 years of sustained elevated uric acid levels, and
the first attack is explosive and intensely painful.  The arthritis
is initially monoarticular, in the lower extremities (usually the first
metatarsal-phalangeal joint), and subsides in 7-10 days.  Some individuals
have only one episode of acute arthritis, others develop recurrences. 
Chronic gout is characterized by persistant polyarticular low-grade pain,
evidenced by destruction of bone and cartilage and is associated with x-ray
changes.
     I suspect after millions of
years of carnivorous diets, T-rex would be well-adapted to a high-purine
diet, and since it would take years of chronically high uric acid levels
to produce the changes seen in fossils, a dietary cause for a T-rex's gout
seems unlikely to me.  I suspect that there was a large genetic variability
in uric acid production/excretion in dinosaurs, and that those on the high
end of the scale would be predisposed to gout.  If their metabolism
is similar to humans, I would expect a T-rex with gout to be male and an
older individual.  As an aside, humans have increased levels of uric
acid compared to prosimians and other lower primates.  Uric acid is
a very powerful antioxident, on the level of vitamin C, and it has been
proposed that it may contribute to human's longer life span although this
has no supporting evidence at present.      Ken
Clay,M.D.