Clinical Trial Details
— Status: Withdrawn
Administrative data
| NCT number |
NCT00120731 |
| Other study ID # |
RG#05036 |
| Secondary ID |
|
| Status |
Withdrawn |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
July 2005 |
| Est. completion date |
May 2007 |
Study information
| Verified date |
November 2020 |
| Source |
Children's Mercy Hospital Kansas City |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
High amounts of calcium in the urine (hypercalciuria) can cause development of kidney stones
in children. Treatment for these children includes plenty of fluids, a low-salt diet and
medications such as potassium citrate. A major advantage of potassium citrate, as compared to
hydrochlorothiazide, is its lack of side effects. One problem the researchers and others have
observed is that some children continue to form kidney stones despite correction of
hypercalciuria with potassium citrate. One possible explanation is that in some individuals
potassium citrate therapy results in an excessive elevation of urine pH, a situation that may
predispose to calcium phosphate stone formation. In this study, the researchers will study
the effects of potassium citrate on urine chemistries and acid-base balance in three groups
of children aged 5-17 years:
- children who are hypercalciuric stone formers;
- healthy children without a history of hypercalciuria or kidney stones.
Particular attention will be paid to try to identify those who develop a very high urine pH
(>8) and the factors leading to this metabolic reaction.
The researchers will try to learn whether it is the child's characteristics, the disease
manifestations, the dose of the drug, or a combination of the above which may be the cause of
the development of very alkaline urine. Based on the results, the researchers hope to be able
to better "tailor" the individual treatment for each child with kidney stones.
Description:
Hypercalciuria is a common clinical pediatric problem that in some children is associated
with renal stones. Most renal stones (80%) are formed by calcium oxalate, calcium phosphate
phases (apatite), and brushite (calcium monohydrogen phosphate). Hypercalciuria can be either
primary (accounts for the vast majority of children with calcium stones) or secondary.
Treatment for children with calcium stones involves non-pharmacological and pharmacological
interventions. Non-pharmacological interventions include high fluid intake, low sodium, and
potassium enhanced diet, with RDA calcium and protein. Historically, the specific treatment
for hypercalciuric stone formers has included thiazides, which reduce calciuria, lower the
urinary saturation of calcium oxalate and phosphate, and restore normal intestinal calcium
absorption. However thiazides induce hypokalemia and hypocitraturia, and the latter
attenuates the beneficial effects of the drug on stone formation. Currently, the drug of
choice replacing thiazides in treating idiopathic hypercalciuria is potassium citrate.
Potassium citrate is readily absorbed from the gastrointestinal tract, and after being
excreted in the urine, it inhibits the crystallization of stone forming calcium salts by
binding the calcium ion, thus decreasing its urinary saturation and inhibiting the nucleation
and crystal growth of calcium oxalate; therefore, potassium citrate is an effective stone
inhibitor agent. A major advantage of potassium citrate is its lack of side effects. One of
the problems seen in clinical practice is that some children with primary hypercalciuria,
even after the calciuria is treated successfully with potassium citrate, continue to develop
stones. It has been suggested that an elevation in urine pH, seen in some patients treated
with potassium citrate, may result in an alkaline urinary milieu which promotes calcium
phosphate stone formation. In this study, the researchers plan to investigate the effects of
potassium citrate on urine chemistries and acid-base balance in children who are
hypercalciuric stone formers. The researchers will try to identify whether the beneficial
effects of potassium citrate supplementation on lowering urine calcium and increasing citrate
might be offset by too high urine pH (>8) which could promote the formation of calcium
phosphate stones. Three groups of subjects aged 5-17 years will be studied: group 1 -
idiopathic hypercalciuric stone formers; group 2 - idiopathic hypercalciuric non-stone
formers; and group 3 - normocalciuric subjects. Three visits will be scheduled for each
participant, and the subjects will receive two doses of potassium citrate. Urine chemistries
and acid-base parameters will be measured. The researchers will try to learn whether it is
the child's characteristics, the disease manifestations, the dose of the drug, or a
combination of the above which may be the cause of the development of very alkaline urine.
Based on the study results, the researchers hope to be able to better "tailor" the individual
treatment for each child with kidney stones due to idiopathic hypercalciuria.
