Only eight of 150 PCP (group 1) patients (5 percent) had normal LDH levels (four had normal chest roentgenograms), while 12 (8 percent) had mildly elevated levels, ranging from 220 to 300 IU/L. In the 67 non-PCP pulmonary AIDS patients (group 2), 55 patients had LDH levels in the normal range (less than 220 IU/L); eight patients had mildly elevated LDH levels ranging from 220 to 300 IU/L (all had biopsies revealing nonspecific interstitial inflammation); four patients (7-percent) had LDH>300 IU/L (two patients with lymphocytic interstitial pneumonia, one patient with pulmonary lymphoma, and one patient with Legionella). Two of 15 nonpulmonary AIDS patients (group 3) had LDH>300 IU/L; both had extrapulmonary lymphoma.
Isoenzyme studies were performed in 50 patients whose mean LDH = 436±29 IU/L. The distribution among the patients was: increased LDH —3/4 = 19; increased LDH — 1 = 1; increased LDH — 2 = 13; increased LDH — 5 = 4; and “normal” or isomorphic isoenzyme distribution = 13.
Seventy-eight percent (117 of 150) of PCP patients in group 1 survived their initial episode of pneumonia. When survivors were compared with nonsurvivors, the mean LDH level was 394 ±45 vs 717 ±51 IU/L (p<0.01), the mean P(A-a)02 gradient was 42 ±6 vs 55 ± 6 mm Hg (p<0.05) and the mean respiratory rate was 18 ±3 vs 27 ±4 breaths/min (p<0.05) (Fig 2). There was no significant difference between survivors and nonsurvivors with respect to duration of symptoms, presence of physical findings (other than respiratory rate), and admission leukocyte or lymphocyte counts. Radiographic presentation had limited prognostic value; all patients with normal findings (ten, among whom six had elevated serum LDH; mean = 345 ± 10 IU/L) survived. this
Serial LDH levels and calculated P(A-a)02 gradients were obtained in 50 survivors (mean initial LDH = 373 ±32 IU/L and mean initial P[A-a]02 gradient =40 ±4 mm Hg) (Fig 3 and 4). LDH levels returned to normal (<220 IU/L) in 26 patients (65 percent) by completion of therapy (mean duration of therapy, 17 ±3 days). In the remaining 14 patients (35 percent), LDH levels fell to less than 300 IU/L by completion of therapy (mean duration of 18 ± 3 days). Twenty-four of the 40 survivors demonstrated a decline in P(A-a)02 gradients to less than 15 mm Hg. The mean P(A-a)02 gradient for the entire 50 patients on completion of therapy was 19 ± 4 mm Hg.
Figure 2. Survivors had a lower mean serum LDH (p<0.01) as well as lower P(A-a)Q2 gradients (p<0.05) than nonsurvivors.
Figure 3. Serum LDH levels returned close to baseline by completion of therapy.
Figure 4. The P(A-a)02 gradients returned to baseline by completion of therapy.