False-Negative Inferior Petrosal Sinus Sampling in Young-Onset Cushing Disease: What Happens Next

In ACTH-dependent Cushing syndrome, identifying the source of cortisol overproduction is critical. Inferior petrosal sinus sampling (IPSS) is a standard diagnostic tool for this purpose. However, false-negative results can obscure diagnosis and delay treatment. Prior research has shown IPSS to be highly specific in most cases, but uncertainty remains about its reliability in younger patients. No prior work had resolved the frequency of false-negative IPSS in patients under 21 years old with Cushing disease. This gap motivated a focused analysis of young-onset cases. Young patients present unique challenges due to overlapping symptoms and variable hormone profiles. The study aimed to clarify how often IPSS fails in this group and what alternative diagnostic steps are necessary. Understanding these patterns could improve clinical decision-making for this vulnerable population.

The goal of this investigation was to assess the diagnostic accuracy of IPSS in patients with young-onset Cushing disease. The researchers focused on patients under 21 years old who underwent IPSS during their evaluation for ACTH-dependent Cushing syndrome. The study aimed to determine how often IPSS results were falsely negative in this demographic. By analyzing a small but distinct cohort, the authors sought to identify management strategies for cases where IPSS fails to confirm pituitary disease. The motivation for this work stemmed from the lack of data on IPSS reliability in young patients. Clinicians often face uncertainty when IPSS results are negative, and this study aimed to guide appropriate follow-up. The findings could help reduce diagnostic delays and improve patient outcomes in this age group.

The researchers reviewed medical records of patients diagnosed with Cushing disease who were under 21 years old at diagnosis. All patients had undergone IPSS as part of their diagnostic evaluation. The study team identified cases where IPSS results were negative but a pituitary tumor was later confirmed via histology or surgical remission. They compared demographic and biochemical data between patients with false-negative IPSS and those with accurate results. No significant differences were found in age, sex, or hormone levels between groups. The authors documented the diagnostic workup for each patient, including repeat IPSS and ectopic source evaluations. Medical treatment was used in some cases to manage cortisol levels before surgery. The study focused on clinical outcomes and management strategies following false-negative IPSS.

Out of 142 IPSS procedures performed in young-onset Cushing disease patients, five were false-negative, affecting four individuals. This represents a 3.5% false-negative rate. Patients with false-negative IPSS did not differ in age, sex, or biochemical markers from others. Three of the four patients underwent additional diagnostic steps, including ectopic source screening and repeat IPSS. Two received medical therapy to suppress cortisol production. One patient proceeded directly to surgery without further evaluation. All four patients eventually had pituitary surgery and achieved remission. These findings suggest that false-negative IPSS is rare but possible in young-onset Cushing disease. The data highlight the need for alternative diagnostic approaches when IPSS results are inconclusive.

The authors concluded that false-negative IPSS results are uncommon but can occur in young-onset Cushing disease. They emphasized the importance of considering alternative diagnostic strategies when IPSS fails to confirm pituitary disease. The study supports screening for ectopic sources of ACTH or CRH secretion in these cases. If ectopic workup is negative, repeating IPSS may be necessary. Medical management can be used to control cortisol levels while awaiting a definitive diagnosis. The findings suggest that young patients with suspected Cushing disease should not be solely reliant on IPSS results. Clinicians should remain alert to the possibility of false-negative IPSS and pursue additional diagnostic options. The authors propose that these management strategies can help avoid diagnostic delays and improve patient outcomes.