Background The interest of monitoring patients treated with several medicines using blood tests has been demonstrated in many publications. However, most citations refer to the outpatient setting. A consensus about ‘drug-laboratory test’ pairs that should be prioritised for follow-up which has been published recently.

Purpose To evaluate the prevalence of prescription drugs that should be monitored by lab tests and how often these test values change, with the aim of establishing the clinical relevance of alerts on ‘drug-laboratory test’ pairs in our hospital.

Materials and methods The authors screened for the blood levels of particular drugs based on a review carried out by earlier researchers (poster presented at 16th Congress EAHP), and the consensus recently published in the American Journal of Health-System Pharmacy. The authors selected 22 ‘drug-laboratory test’ pairs. The authors reviewed the pharmacological treatment of all patients admitted to internal medicine and psychiatry for a month. These wards were chosen by the greater likelihood of finding treatments with the selected drugs. The authors assessed the prevalence of prescriptions for the selected drugs, and also looked for laboratory test values that were likely to be altered as the result of taking these medicines.

Results The authors checked 122 patients treated with some of the selected drugs, of whom 109 were in internal medicine and 13 in psychiatry. 50% of the patients were women. The average age was 72±17.5 years, and the average stay of 7.2±4.9 days. Patients taking some of the selected drugs corresponded to 64.6% of patients admitted during the study period. 351 drugs were selected, with an average of 2.9 drugs per patient. The overall incidence of patients with some drug associated with abnormal laboratory tests was 60 cases per 100 patients. Numbers of patients found with ‘drug-abnormal analysis’ pairs are shown in the following table:

Conclusions The high prevalence in our hospital of patients with prescribed medicines included in the selected alerts and the high incidence of lab test abnormalities associated with their prescription drugs highlights the importance of performing this type of monitoring from the pharmacy department, since it may affect the patient's clinical situation. The drug-abnormalities analytical pairs most often found have been creatinine increase- nephrotoxic drugs, diuretics high efficiency-hypokalaemia, thrombocytopenia-LMWH, and hyperkalaemia-drugs that increase serum potassium, suggesting the appropriateness of prioritising these alerts in the monitoring pharmacotherapy.