
Thyroid hormone, anemia and elderly diabetic nephropathy   159
Vol. 66(2): 157 - 165, 2025
on the hypothalamic-pituitary-thyroid axis 
function with the progression of the disease, 
the synthesis of thyroid hormones declines 
in DN patients, and thyroid dysfunction oc-
curs. Thyroid hormones may be implicated 
in glomerular filtration rate (GFR) regula-
tion and blood circulation in the kidneys 4. 
The rate of thyroid function abnormality in 
patients with kidney disease at stage G5 is 
significantly higher than that at stage G1 
(39.1% vs. 8.3%), and it is considered that 
the severity of kidney disease may be closely 
related to thyroid function 5. Moreover, the 
severity of type 2 diabetes mellitus (T2DM) 
in elderly patients also correlates with blood 
glucose-related indicators and thyroid hor-
mone levels. Free triiodothyronine (FT3), 
free thyroxine (FT4) and other thyroid hor-
mones in mild and severe T2DM in elderly 
patients are at significantly lower levels 
than in healthy controls 6, suggesting that 
the changes in thyroid hormone levels may 
be related to the severity of T2DM in elderly 
patients. However, no reports are available 
yet on whether thyroid hormone level is re-
lated to the severity of anemia in elderly DN 
patients.
Because of this, the level changes of 
thyroid hormones in patients with different 
severities of anemia were analyzed in this 
study to explore the correlations of thyroid 
hormones with anemia severity in elderly DN 
subjects, aiming to provide a reference for 
diagnosis and treatment in clinical practice.
PATIENTS AND METHODS
Subjects
One hundred and forty older adults di-
agnosed with DN and hospitalized for treat-
ment herein during November 2019 and De-
cember 2023 were retrospectively recruited 
into the DN group. The following inclusion 
criteria were utilized: 1) patients satisfying 
the diagnosis and classification criteria for 
diabetes mellitus in the Guideline for Pre-
vention and Treatment of Type 2 Diabetes 
Mellitus in China (2020 Edition) 7, 2) those 
who met the diagnostic and treatment cri-
teria for DN 8, 3) those with urinary albu-
min  excretion  rate  (AER)  ≥30  mg/24  h, 
GFR≤60 mL/min·1.73 m2 or urinary micro-
albumin/creatinine  ratio  (ACR)  ≥3  mg/g, 
and 4) those without renal transplantation 
or dialysis history. The adopted exclusion 
criteria included: 1) patients who had taken 
drugs that may affect urinary protein excre-
tion before participating in the study, 2) 
those with no obvious hepatic and renal dys-
function previously and no severe complica-
tions of diabetes mellitus recently, 3) those 
complicated with other kidney diseases, or 
4) those complicated with mental illness or 
cognitive dysfunction. Another 140 patients 
with uncomplicated diabetes mellitus en-
tered the simple diabetes group, in addition 
to 140 healthy subjects as the healthy group. 
Their gender, age, and body mass index were 
not significantly different from those in the 
DN group.
Grouping criteria
According to the GFR, patients with 
chronic DN were divided into stage 5 group 
(n=11, GFR<15 mL/min·1.73 m2), stage 4 
group (n=20, 15 mL/min·1.73 m2≤GFR<30 
mL/min·1.73 m2), stage 3 group (n=43, 30 
mL/min·1.73  m2≤GFR<60  mL/min·1.73 
m2), stage 2 group (n=39, 60 mL/min·1.73 
m2≤GFR<90 mL/min·1.73 m2), and stage 1 
group (n=27, GFR≥90 mL/min·1.73 m2).
An anemia group (n=77) plus a non-
anemia group (n=63) were established as 
subsets of the DN group according to the 
hemoglobin (Hb) level. Hb ≤120 g/L in fe-
males and ≤130 g/L in males indicated ane-
mia.
The anemia group was further divided 
into a severe group (n=48) (Hb<60 g/L), 
a moderate group (n=16) (60 g/L≤Hb<90 
g/L) and a mild group (n=13) (Hb≥90 g/L).
Detection of thyroid hormones
All patients were enrolled to collect fast-
ing venous blood (5 mL) in the morning for 
centrifugation. Then, the supernatant was