Which symptom suggests that blood levels of aspirin are too high and the client is experiencing salicylism?

Choice A rationale: Allopurinol dosing is not typically adjusted based on target serum drug levels.
Choice B rationale: The absence of gastrointestinal (GI) effects is not a parameter used to adjust the dosing of allopurinol.
Choice C rationale: This is partially correct. Allopurinol dosing is adjusted based on renal function, but specifically, it is adjusted based on serum creatinine levels. The higher the creatinine levels, the lower the dose of allopurinol should be.
Choice D rationale: This is correct. Allopurinol dosing is adjusted based on plasma urate levels. The goal is to reduce uric acid levels in the blood to prevent the formation of urate crystals and subsequent gout attacks. Regular monitoring of plasma urate levels helps determine the effectiveness of the medication, and adjustments can be made to achieve the target urate level.

Choice A rationale: Adjusting the dose based on symptoms is not appropriate for phenytoin. It should be taken consistently as prescribed.
Choice B rationale: While taking phenytoin with meals is a general recommendation, it is not the priority teaching point.
Choice C rationale: Informing the patient about the prevention of gingival hyperplasia is important but not the top priority.
Choice D rationale: Teaching the patient to avoid the abrupt cessation of treatment is crucial. Abruptly stopping phenytoin can lead to seizures, and patients should be advised to taper the medication under medical supervision.