NAG level differences in panic disorder and agoraphobia.

It is not clear if panic disorder (PD) and agoraphobia are variants of the same disorder or distinct diseases. A laboratory test could help resolve this issue. Research has shown that levels of the urinary lysosomal enzyme N-acetyl-beta-glusosaminidase (NAG) differ between patients with various psychiatric disorders. This study examined whether NAG levels would be similar in PD and agoraphobia, suggesting the two disorders may be the same disorder, or different, suggesting they may be distinct diseases. Differences found could suggest either qualitative or quantitative distinctions between these disorders. Ninety-one agoraphobics were compared to 24 patients with panic disorder. NAG levels were significantly lower in panic patients compared to agoraphobic patients 9.7+/- 8 versus 22+/- 21; P< .005. These data provide limited support for the hypothesis that PD and agoraphobia may be distinct diseases.

Urinary excretion of cortisol, norepinephrine, testosterone, and melatonin in panic disorder.

Nocturnal urinary cortisol, norepinephrine, epinephrine, testosterone, and melatonin secretion patterns were studied in male patients with DSM IV/ICD-10 panic disorder (n = 16) over two series of 5 consecutive nights each. Night-time urinary excretion of cortisol, norepinephrine, and epinephrine was significantly elevated in drug-free patients compared to normal individuals (n = 13). Measurements were repeated after 4 weeks, and the same differences were found again. There were high correlations between the first and the second series of measurements. Testosterone and melatonin levels did not differ between panic patients and controls.

Comparison of panic disordered patients with high versus low MHPG.

Fourteen panic disorder patients with low 3-methoxy-4-hydroxyphenylglycol (MHPG) were compared to 14 patients with high MHPG. Patients with low MHPG were more likely during the preceding month to have experienced spontaneous panic attacks (P less than 0.008) than were patients with high MHPG. Patients with high MHPG had increased severity ratings on several individual symptoms of anxiety.

Direct comparison of urinary free cortisol excretion in patients with depression and panic disorder.

Urinary free cortisol (UFC) excretion in 31 patients with major depression is directly compared to UFC levels in 65 patients with panic disorder and 36 controls. Patients with depression demonstrated significantly higher UFC excretion [43 +/- 37 micrograms/g creatinine (cr)] than patients with panic disorder (29 +/- 13 micrograms/g-cr) or controls (22 +/- 10 micrograms/g-cr) (F = 8.5, df = 129, p less than 0.001). Panic patients with a secondary depression (35 +/- 17 micrograms/g-cr) or those with agoraphobia (34 +/- 14 micrograms/g-cr) had UFC levels that were in-between patients with primary major depression and panic patients without these complications (25 +/- 11 micrograms/g-cr). These findings support the hypothesis that patients with major depression, whether primary or secondary, and those with agoraphobia excrete more UFC than patients with uncomplicated panic disorder. This occurs despite the fact that panic disorder might also be expected to raise the stress-responsive hormone cortisol.

Relationship of urinary free cortisol levels in patients with panic disorder to symptoms of depression and agoraphobia.

Sixty-five patients with panic disorder and 37 matched controls collected 24-hour urine specimens for measurement of urinary free cortisol. Although patients with panic disorder had significantly higher urinary free cortisol levels than control subjects, this difference was accounted for by panic disorder patients with concomitant depression, agoraphobia, or both. Urinary free cortisol excretion was not related to the age of onset of panic disorder, the number of spontaneous panic attacks, or the degree of impairment associated with the disorder. They were related, however, to the level of symptoms on both the Hamilton Rating Scale for Depression and the Hamilton Rating Scale for Anxiety in the entire group of panic patients, but this relationship disappeared when those patients with the complications of agoraphobia and depression were excluded. These data suggest that, as with primary depression, depression secondary to panic disorder, as well as to agoraphobia in panic disorder patients, is associated with hyperactivity of the hypothalamic-pituitary-adrenal axis.