Quantitation of Serum C-reactive Protein and Its Change in Pathologic Conditions : (II) Extremely Low Levels in Malignant Neoplasms

Serum CRP (C-reactive protein) has been determined as a marker of inflammation and tissue damage. The clinical significance of its quantitation in the low concentration range in adults has not yet been well clarified, although highly-sensitive CRP immunoassay for lower concentrations (<0.4μg/dl) has been applied only to the diagnosis of infection in neonates. Therefore, we first determined the normal value in healthy adults. Then, we monitored CRP levels in patients with hematopoietic tumor, cancer with hormone synthesis, etc. and found that CRP decreased after steroid therapy. CRP was determined by PAMIA-30 [SYSMEX, Japan] or LPIA-300 [DIA-IATRON, Japan]. α_1-antitrypsin (α_1 AT), haptoglobin (HP), α_1-acidglycoprotein (α_1 AG), and complement C3 (C3) were determined by BNA [HOECHST, Japan]. Interleukin 6 (IL-6) was determined by enzyme immunoassay with chemiluminescence. Among 70 patients with cancer, relatively low CRP were found in cancer of the hormone-producing tissues (pituitary adenoma, adrenal cancer, pancreatic carcinoma, thyroid neoplasm, etc.), cancer in females (mammaly cancer and some patients with cancer of the uterus and ovarian tumor), cancer of tongue and prostatic cancer. From this survey, we found that CRP levels were low in patients under steroid therapy. In hematopoietic tumors of ALL, AML, myeloma and lymphoma, CRP also decreased markedly after steroid therapy. In contrast, CRP levels did not change in CML without administration of steroids. We monitored CRP, some other acute phase proteins and IL-6 in patients with malignant lymphoma. CRP values decreased from 36435μg/dl to 12μg/dl after treatment. Other acute phase proteins, such as α_1 AT, HP, α_1 AG and C3, were also monitored for these patients. It was found that only CRP responded sensitively. CRP decreased soon after steroid administration, and the level remained low. The other four acute phase proteins started to decrease later than CRP. From these findings it is suggested that quantitation of low CRP levels in serum may be useful in monitoring in patients with malignant neoplasm undergoing chemotherapy.