Demographics and Predictive Clinical-Laboratory Parameters of Systemic and Hepatic AA Amyloidosis - A Postmortem Clinicopathologic Study of 152 Rheumatoid Arthritis Patients

The aim of this study was to determine the demographics of systemic AA amyloidosis syndrome (sAAa), and hepatic AA amyloidosis (hAAa) in rheumatoid arthritis (RA), to assess the predictive clinical laboratory parameters.

Patients (autopsy population) and Methods: The demographics and clinical laboratory parameters were analyzed based on 152 autopsy patients with RA. RA was confirmed clinically according to the criteria of the American College of Rheumatology (ACR). The patients were treated and died in one institute (National Institute of Rheumatology, Budapest, Hungary) between 1969 and 1992.

The sAAa and hAAa was specified histologically, based on evaluation of five organs (kidneys, heart, pancreas, lungs, and liver).

Amyloid A deposition in different tissue structures of various organs was diagnosed histologically according to Romhányi, by a modified (more sensitive) Congo red staining.

The correlations were determined by the Student (Welch) t-probe, comparing the age, sex, onset of RA, duration of disease, and classic laboratory parameters at the last hospitalization with or without sAAa or hAAa.

Results and Conclusions: Amyloidosis may develop in both sexes and at any time of the disease.

The diagnostic values of the discussed laboratory parameters are limited, and none are specific for amyloidosis.

The more or less significant differences between RA patients with and without sAAa show the impaired function of the kidneys or are connected to the basic disease only.

There is no significant difference in classic laboratory parameters between cohorts of RA patients with sAAa and hAAa.

For exact diagnosis of amyloidosis a biopsy is needed using an „appropriate staining procedure”. Gingival or rectal biopsies are suggested. The increased erythrocyte sedimentation rate associated to laboratory parameters of impaired renal function arises the possibility of hAAa, and especially in hepatomegaly, a liver biopsy may be considered to confirm hAAa.

Keywords: Rheumatoid arthritis, demographics, clinical laboratory parameters, systemic AA amyloidosis, AA amyloidosis of the liver.