BACKGROUND: Low T3 is a frequent alteration in patients with ESRD. This 
derangement has been recently linked to inflammation in haemodialysis patients. 
Whether this association holds true in peritoneal dialysis patients has not been 
studied.
METHODS: We investigated the relationship between low-grade inflammation [IL-6, 
C-reactive protein (CRP) and serum albumin levels] and free tri-iodothyronine 
(fT3) in a cohort of 41 CAPD patients (mean age, 66 years; M, 26; F, 15) without 
heart failure and inter-current illnesses.
RESULTS: CAPD patients had lower fT3 levels (2.7 +/- 0.8 pg/ml) than healthy 
subjects (3.7 +/- 1.0 pg/ml, P < 0.001) of similar age. Free T3 levels were 
directly related to those of serum albumin (r = 0.52, P = 0.001) and inversely 
to IL-6 (r = -0.30, P = 0.05) and CRP (r = -0.54, P < 0.001). Age (r = -0.61, P 
< 0.001), haemoglobin levels (r = 0.32, P = 0.05) and diastolic blood pressure 
(r = 0.50, P = 0.001) were also related to fT3. In multiple regression models 
adjusting for all variables related to fT3, CRP and albumin were retained as 
independent correlates of fT3. During the follow-up (2.8 +/- 1.7 years) 27 
patients died. Plasma fT3 levels were lower in patients who died (2.5 +/- 0.8 
pg/ml) compared with survivors (3.3 +/- 0.5 pg/ml P = 0.001). In Cox analyses, 
fT3 was a significant predictor of mortality independent of the main traditional 
as well as non-traditional risk factors.
CONCLUSIONS: The relationship between fT3, CRP and serum albumin suggests that 
inflammation-malnutrition might be involved in the low T3 syndrome in CAPD 
patients. Thyroid dysfunction might be implicated in the pathogenic pathway 
which links micro-inflammation to survival in PD patients.