Crystalluria - the presence of crystals in urine - simply means that the urine specimen is oversaturated with crystallogenic substances; however, numerous variables influence crystalluria. The significance of crystalluria is easily misjudged if these factors are not considered. In vivo (within the body) variables include urine concentration, urine pH, amount and solubility of crystalloids, presence of crystallization promoters and inhibitors, and excretion of medications or diagnostic agents. In vitro (outside the body) variables include temperature, evaporation, pH, and technique of specimen preparation. It is important to note that refrigeration of urine samples leads to precipitation of crystal, a falsely positive result.
What does all this mean? It means that the presence of crystals in urine is usually clinically insignificant. Specific crystals, however, such as ammonium biurate crystals, can indicate hepatic insufficiency. Crystalluria can often cause concerns about urolithiasis (stones) but crystalluria must not be the sole criterion for assessment of stone composition nor do animals with crystalluria necessarily form stones.
In summary, the presence of crystals is usually normal. The above said, I need to know which type of crystals were found in your 2.5 year old and if she were symptomatic of a urinary disorder at the time crystals were found. Please note that altering the pH may be necessary when addressing calculi (stones) which essentially are crystals that have come out of solution but otherwise we're more interested in diluting the urine which then doesn't allow oversaturation of the crystals which then might allow precipitation of stones. In addition, unless multiple readings over many days reveal a persistently low or high pH of the urine, we can't be sure that any one pH finding indicates the true acid/base state of a patient's urine. The pH of urine can change from 6.5 to 7.5 many times throughout a 24 hour period depending upon diet and other metabolic processes ongoing.
Please respond with further questions or concerns if you wish.