# Preoperative Metabolic Predictors of Granulation Subtypes in Somatotroph Tumors: A Multicenter Retrospective Cohort Study

## TL;DR

This study shows that a combination of triglycerides and uric acid can help identify a more aggressive type of pituitary tumor before surgery.

## Contribution

The TG–UA index is proposed as a novel, noninvasive biomarker for preoperative differentiation of SGSTs from DGSTs.

## Key findings

- SGSTs were associated with higher TG, GH, IGF-1, and TG–UA index values.
- The TG–UA index remained an independent predictor of SGST subtype (OR = 1.514, p = 0.014).
- The TG–UA index is a promising noninvasive biomarker for identifying SGSTs.

## Abstract

Differentiating between sparsely granulated and densely granulated somatotroph tumors (SGSTs and DGSTs) currently relies on postoperative immunohistochemistry. This study aimed to evaluate whether triglyceride (TG), uric acid (UA), and their composite TG–UA index [ln(TG × 1000/UA)] could serve as preoperative indicators for distinguishing granulation subtypes of somatotroph tumors.

In this multicenter retrospective cohort study, 230 patients with somatotroph tumors were analyzed. Logistic regression and generalized additive models assessed associations and potential nonlinear associations between metabolic indicators and granulation subtypes. Predictive performance was compared between models using UA and TG separately and those using the TG–UA index.

SGSTs were associated with significantly higher TG, growth hormone, insulin‐like growth factor 1, and TG–UA index values. The TG–UA index remained an independent predictor of the SGST subtype (OR = 1.514, p = 0.014). Predictive performance was similar between models (p = 0.108).

The TG–UA index is a promising noninvasive biomarker for identifying the SGST subtype in somatotroph tumors. Although limited by its retrospective design and lack of long‐term data, this study provides a foundation for future prospective validation.

Somatotroph tumors, a rare subtype of pituitary adenomas, can be histologically classified into sparsely granulated (SGSTs) and densely granulated somatotroph tumors (DGSTs) based on cytokeratin staining. SGSTs are generally more invasive and less responsive to medical therapy, making their early identification clinically important. This study identified an independent association between the TG–UA index and granulation subtypes and, for the first time, proposed the TG–UA index [ln((TG × 1000)/UA)] as a novel, noninvasive, and cost‐effective biomarker for the preoperative differentiation of SGSTs from DGSTs.