The phrase "a fall in psa" is correct and usable in written English.
It can be used in contexts discussing changes in levels or measurements, particularly in medical or scientific discussions related to prostate-specific antigen (PSA) levels.
Example: "The recent tests showed a fall in psa, indicating a positive response to the treatment."
Alternatives: "a decrease in psa" or "a drop in psa".
Commonly the PSA rose after chemotherapy commenced, prior to its falling and in some cases, a fall in PSA was seen as a late event.
The remaining four men did not show a fall in PSA.
A fall in PSA or stable levels was seen in 13 (52%) of patients at 1 month, 11 (44%) at 2 months, and eight (32%) at 3 months.
Of these, three (18.8%) showed a fall in PSA of at least 50%, representing 15% of the 20 patients initially recruited with the intention to treat.
There was in addition one who received diethylstilbestrol and dexamethasone immediately after progression on CL56, and responded with a fall in PSA of 45%.
Six of the 16 patients for whom data were available showed a fall in PSA after starting thalidomide, which was sustained while taking the drug.
In all, 12 patients did not maintain the fall in PSA after completion of treatment.
13 out of 13 patients with a rising PSA had disease localised by the immune scan and treatment of patients with immune scan-positive sites led to a fall in PSA[ 14].
Rosenberg, A, Darwinism Today Tomorrow, But Not Yesterday, in PSA 1984, edited by Kitcher, P; Asquith, P, vol. 2 (1985), pp. 157-173, East Lansing, MI: Philosophy of Science Association.
We found a significant increase in COL2A1 (fold change of 10.48) in PsA synovium compared with normal synovium.
Patients with RA and those with PsA treated with infliximab also showed greater improvement in the mental component summary score than those in the placebo group with an effect size of 4.6 (4.2 5.1) in RA and 2.7 (2.4 3.1) in PsA.
