Department of Clinical Biochemistry and Pharmacology, 37742 Tomas Bata Hospital Zlín , Zlín, Czech Republic.
Institute of Clinical Biochemistry and Diagnostics, Medical Faculty in Hradec Králové, Charles University, Prague, Czech Republic.
Clin Chem Lab Med. 2024 Jul 30;63(1):129-138. doi: 10.1515/cclm-2024-0773. Print 2025 Jan 29.
Stability of concentrations of urinary stone-related metabolites was analyzed from samples of recurrent urinary stone formers to assess necessity and effectiveness of urine acidification during collection and storage.
First-morning urine was collected from 20 adult calcium-stone forming patients at Tomas Bata Hospital in the Czech Republic. Urine samples were analyzed for calcium, magnesium, inorganic phosphate, uric acid, sodium, potassium, chloride, citrate, oxalate, and urine particles. The single-voided specimens were collected without acidification, after which they were divided into three groups for storage: samples without acidification ("NON"), acidification before storage ("PRE"), or acidification after storage ("POST"). The analyses were conducted on the day of arrival (day 0, "baseline"), or after storage for 2 or 7 days at room temperature. The maximum permissible difference () was defined as ±20 % from the baseline.
The urine concentrations of all stone-related metabolites remained within the 20 % limits in NON and POST samples after 2 days, except for calcium in NON sample of one patient, and oxalate of three patients and citrate of one patient in POST samples. In PRE samples, stability failed in urine samples for oxalate of three patients, and for uric acid of four patients after 2 days. Failures in stability often correlated with high baseline concentrations of those metabolites in urine.
Detailed procedures are needed to collect urine specimens for analysis of urinary stone-related metabolites, considering both patient safety and stability of those metabolites. We recommend specific preservation steps.
分析复发性尿路结石患者尿液中与结石相关代谢物的浓度稳定性，以评估收集和储存过程中尿液酸化的必要性和有效性。
在捷克共和国托马斯·巴塔医院，收集了 20 名成年钙结石形成患者的晨尿。对尿液样本进行钙、镁、无机磷酸盐、尿酸、钠、钾、氯、柠檬酸、草酸盐和尿颗粒分析。单次排空的标本未经酸化收集，然后分为三组储存：未酸化组（“NON”）、储存前酸化组（“PRE”）或储存后酸化组（“POST”）。分析在到达当天（第 0 天，“基线”）或在室温下储存 2 或 7 天后进行。最大允许差异（）定义为与基线相比±20%。
除一名患者的 NON 样本中的钙和三名患者的 POST 样本中的草酸盐以及一名患者的 POST 样本中的柠檬酸外，所有与结石相关的代谢物的尿液浓度在 NON 和 POST 样本中在 2 天后仍保持在 20%的范围内。在 PRE 样本中，三名患者的尿液草酸盐和四名患者的尿液尿酸在 2 天后的稳定性失败。稳定性失败通常与这些代谢物在尿液中的基线浓度较高有关。
考虑到患者安全和代谢物稳定性，需要详细的程序来收集尿液样本以分析与结石相关的代谢物。我们建议采取具体的保存步骤。
