Pneumocystis carinii pneumonia continues to be the most frequent pulmonary manifestations of AIDS. Its subtle, subacute presentation has been well documented; a high index of suspicion must be maintained, because there are few clinical or laboratory clues to the diagnosis. The rate of recovery from a first bout of Pneumocystis has ranged from 50 to 80 percent. The duration of symptoms does not correlate with prognosis. Rather, the degree of respiratory distress on presentation as measured by respiratory rate, room air Pa02 as well as P(A-a)02 gradient have prognostic value.
Early in the AIDS epidemic, we presented preliminary data suggesting the diagnostic and prognostic value of elevations in serum LDH in patients with Pneumocystis.6 H Subsequently, Silverman and Rubinstein found an elevation in serum LDH in 12 patients with Pneumocystis and suggested that it might be a laboratory indicator of P carinii pneumonia. Extremely high levels of LDH appeared to reflect more extensive interstitial inflammation and declined with successful therapy. Increased LDH values were also seen in five pediatric cases of LIP and one adult with pulmonary Kaposi’s sarcoma. Zaman and White recently found an increase in serum LDH in patients with Pneumocystis (mean, 361 IU); however, they noted an overlap in HIV-infected patients with PCP and other causes of pulmonary disease. The isolated elevation of serum LDH levels in AIDS patients with Pneumocystis pneumonia appears to distinguish the Pneumocystis from other pulmonary processes in these patients with sensitivity = 0.94 and specificity = 0.82. Only 5 percent of patients with proved PCP had normal LDH levels. Zaman and White found normal serum LDH in 7 percent of proved PCP patients. Biopsy or lavage confirmation of Pcarinii pneumonia is still necessary for the diagnosis. Mild elevations in serum LDH were observed in patients with nonspecific interstitial pneumonitis, lymphoma, LIP, and Legionella, but in no patient with pulmonary Kaposi’s sarcoma.