Tandem mass spectrometry can be used to detect

• A. 25 to 30 metabolic diseases
• B. Cystic fibrosis
• C. Combined immune deficiency
• D. Panhypopituitarism

Answer: (A)

Tandem mass spectrometry is used in newborn screening to detect multiple inherited metabolic disorders by measuring specific metabolites in dried blood spots. Its multiplex capability allows a single test to flag patterns of amino acids and acylcarnitines that indicate a range of metabolic diseases, typically about 25 to 30 different conditions across amino acid disorders, organic acidemias, and fatty acid oxidation disorders. That breadth of detectable disorders is what makes this technique especially valuable for screening.

Cystic fibrosis is usually screened with a different approach—an immunoreactive trypsinogen test (IRT) followed by genetic testing for CFTR variants, not primarily by tandem MS. Combined immune deficiency and panhypopituitarism are immunologic or hormonal disorders, respectively, and are diagnosed through immune function tests or hormone assays and targeted clinical evaluation, not through the metabolic pattern screening provided by MS/MS.