Horm Metab Res
DOI: 10.1055/a-2301-3225

1   Institute for Clinical Chemistry, Laboratory Medicine and Transfusion Medicine, General Hospital Nuremberg and Paracelsus Medical University, Nuremberg, Germany

,

Thomas Bertsch

1   Institute for Clinical Chemistry, Laboratory Medicine and Transfusion Medicine, General Hospital Nuremberg and Paracelsus Medical University, Nuremberg, Germany

Dear Editor,

The study of Zhang et al. [1] exhibits a significant selection bias, which should have been addressed. It is not understandable, why patients with hyperprolactinemia were excluded from the study population, when prolactin levels are the main factor under investigation. It may have escaped the attention of the authors, that prolactin levels beyond the classical upper thresholds may represent a homeostatic functionally increased transient prolactinemia (HomeoFIT-PRL), or primary regulatory hyperprolactinemia, apart from secondary etiologies such as drug-induced hyperprolactinemia, prolactinoma, or others [2]. The minimum requirement, which is needed to assess the validity of the study and estimate the impact of the bias is the number of patients excluded due to hyperprolactinemia and the prolactin level thresholds that were used for exclusion. The use of SI-units and a specification of which Siemens assay and platform were used would have further improved the quality of the study.

Sincerely,

Jakob Triebel, MD

Thomas Bertsch, MD

Article published online:
02 May 2024

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