Let's move on to uric acid stones.
What are specific considerations for those stone formers?
So, risk factors for stone formation in this population include hyperuricosuria.
That has to do with potentially dietary protein intake,
particularly if they have high purine intake,
disorders due to the breakdown of cells like tumor lysis syndrome
that releases uric acid into the circulation, gout,
like our patient, or inborn errors of metabolism like Lesch-Nyhan syndrome.
Patients with a low urinary pH,
remember that low urinary pH are going to precipitate uric acid stones.
And then a low urine volume.
So, how about the treatment in our patients who form uric acid stones?
Some of the general treatments we discussed earlier
play an important role in uric acid stone formers as well.
This includes an increase in fluid intake to produce greater than 2-2.5 L of urine,
reduced animal protein and purine intake,
but most importantly is alkalinization of the urine.
We could use either potassium citrate or potassium bicarbonate to achieve this.
This will facilitate raising the urinary pH to ideally, greater than 6.5,
and that will allow most of the urinary uric acid to exist in the more soluble urate salt,
minimizing the risk of uric acid precipitation.
If the patients continue to form uric acid stones despite alkali therapy
and an increase in fluid intake, then allopurinol
can be used in doses of 100-300 mg daily in order to reduce urinary uric acid
to less than 750 mg daily.