For which condition is a lumbar puncture indicated as a diagnostic step?

A lumbar puncture is indicated as a diagnostic step primarily for idiopathic intracranial hypertension (IIH). IIH is characterized by increased intracranial pressure without an identifiable cause on neuroimaging, and the procedure can help confirm the diagnosis. During the lumbar puncture, cerebrospinal fluid (CSF) pressure measurements can be taken, and analysis of the CSF may help rule out other conditions.

In patients suspected of having IIH, lumbar puncture serves multiple purposes: it can relieve some of the pressure, potentially alleviating symptoms, and it provides valuable information regarding the composition of the cerebrospinal fluid. This is crucial in distinguishing IIH from other forms of secondary intracranial hypertension, where identifiable causes such as tumors or infections may exist.

In contrast, obesity, diabetes, and hypertension do not typically require lumbar puncture as part of their diagnostic workup. These conditions can generally be diagnosed through clinical assessment, history-taking, and other laboratory tests. Thus, the use of a lumbar puncture is specifically relevant for the diagnostic evaluation of IIH.