Endocrine Abstracts (2009) 20 P24

Characterization of tyrosine hydroxylase expression in various adrenal tumors to confirm the diagnosis of adrenal pheochromocytomas

Bianca Ueberberg1, Jakob Hinrichs2, Martin K Walz2, Kurt W Schmid3, Klaus Mann1 & Stephan Petersenn1


1Division of Endocrinology, Medical Center, University of Duisburg-Essen, Essen, Germany; 2Department of Surgery and Center of Minimally Invasive Surgery, Kliniken Essen-Mitte, Essen, Germany; 3Institute of Pathology, University of Duisburg-Essen, Essen, Germany.


Background: Tyrosine hydroxylase (TH) is the first enzyme in the pathway of catecholamine synthesis catalyzing the conversion of tyrosine to dihydroxyphenylalanine (DOPA). To establish a molecular marker for adrenal pheochromocytomas, we compared the expression in various adrenal tumors in comparison to normal adrenal glands.

Methods: Tissue from 19 pheochromocytomas (PHEO), 20 aldosterone-producing adenomas (APA), 20 cortisol-producing adenomas (CPA), and 20 non-functional adenomas (NFA) was obtained following laparoscopic surgery. Seven normal adrenal glands were obtained during autopsy. The diagnosis was confirmed by various biochemical tests, histological investigation, and clinical follow-up. Extracted RNA underwent Real Time RT-PCR using TH specific primers and probe (detection limit 3.2×102 copies/μg RNA (cp)). mRNA levels were normalized to GAPDH mRNA levels. ROC analysis was performed to established cut-offs with specificity of at least 95%.

Results: PHEO demonstrated higher TH expression with a median of 8.6×106 cp (range 7.2×104–4.3×107 cp) than detected in normal adrenal glands with a median of 1.1×106 cp (range 7.4×103–1.8×107 cp). In contrast, expression was significantly lower (P<0.001) in APA, CPA, and NFA with 2.8×104 cp (3.5×102–1.6×106 cp), 5.3×103 cp (7.5×102–2.5×105 cp), and 6.6×103 cp (3.2×102–1.5×107 cp), respectively. ROC analysis suggested a threshold of 1.1×106 cp with a sensitivity of 95% and specificity of 95%. No significant correlations were found between TH expression and nor-/metanephrine levels, chromogranin A levels or tumor size.

Conclusion: Characterization of TH expression may serve as a molecular marker to distinguish adrenal pheochromocytomas from other adrenal neoplasms. Such criteria could be used to evaluate biochemical tests for the diagnosis of these tumors.

Article tools

My recent searches

No recent searches.