Medical laboratory reports should be comprehensive and support physicians in advising their patients. Therefore, they should include at least the information listed in the Table 1 which might serve as an example of a report. While many laboratories currently supply substantial information, they frequently fail to specify the type of guide limit applied (reference limit or interval, clinical decision limit, or therapeutic limit). The term “guide limits” was taken from ref. [1].

Table 1:

Recommendation of a medical laboratory report.

1. ^a RI, reference interval with lower reference limit (lRL) and upper reference limit (uRL); DL, decision limit; TL, therapeutic limit.

It is, therefore, recommended to include a column after the guide limit to identify the type of guide limit, since patient results require specific guide limits for their interpretation. The different types of guide limits help physicians to interpret the results of quantitative laboratory tests appropriately [1]. The laboratory should define the various types of guide limits in its manual.

The reference interval – or, when only a single boundary is available, the reference limit (e.g. S-lipase in the Table 1) – typically corresponds to the 95 % interval. In some cases, a 99 % interval is used (e.g., troponin), in which case the 99 % reference interval must be mentioned in the laboratory manual.

The specimen type should be specified using the following abbreviations: e.g. “P” for plasma, “S” for serum, “CSF” for cerebrospinal fluid, “U” for urine, and “F” for feces. Of course, in some cases, it might be advisable to use country-specific abbreviations rather than international ones. Instead of these prefixes (abbreviations), the specimen type can be described in headings as “serum / plasma, urine, etc.

Sources of guide limits (“Source”, shown in italics) should be described in the laboratory manual, along with any stratification of guide limits by sex or age. “Source” is set in italics because this information is not part of the report and should be described in the laboratories manual. Age stratification can be modelled continuously using certain indirect methods (e.g. ref. 3). In such cases, guide limits should be reported relative to the patient’s specific age. Such modeling is presently not reportable in most laboratory information systems.

The line labeled “Date” indicates the date on which the specimen was collected. The line labeled “Daytime” indicates either the time of specimen collection (preferred) or, if that is not available, the time the specimen arrived at the laboratory. Specifying the time is essential when reference or guide limits vary by time of day.

With the introduction of standardized, EU-wide harmonized laboratory reports and electronic patient records, additional information will likely be required [6]. Semantic and syntactic standards must be taken into account here. In particular, laboratory results originating from different laboratories should be clearly identifiable (line labelled lab.id. is optional).

The working group published recommendations and a checklist useful for a self-assessment [7].

Original Paper:

Haeckel, Rainer, Streichert, Thomas, Wosniok, Werner, Sonntag, Oswald and on behalf of the Section Guide Limits of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL),. „Recommendations for guide limits related information on a laboratory report“ Journal of Laboratory Medicine. https://doi.org/10.1515/labmed-2025-0283