54
Appendices
Total T
4
Protocols
CBC = Complete blood count
Note:
1 µg/dL is equal to 12.87 nmol/L. A result
that falls within the low normal range of the assay
should be considered ambiguous.
Canine hypothyroidism suspected
Initial database
• Total T
4
• CBC
• Chemistry with
electrolytes
• Complete urinalysis
Low T
4
<1.0 µg/dL
(<13.0 nmol/L)
Low T
4
with NTI
<1.0 µg/dL
(<13.0 nmol/L)
Normal T
4
2.0–4.0 µg/dL
(26.0–51.0 nmol/L)
Hypothyroidism unlikely
fT
4
+
TSH ± TgAA
Low fT
4
± high TSH
± positive TgAA
Hypothyroidism likely
Clinical trial
Hypothyroidism unlikely
Repeat testing in 4–6 weeks if
hypothyroidism still suspected
Normal fT
4
and TSH
negative TgAA
Address NTI
Low Normal T
4
1.0–2.0 µg/dL
(13.0–26.0 nmol/L)
Common clinical
signs in dogs
• Obesity
• Skin disease
• Lethargy
• Mental dullness
• Exercise/Cold intolerance
