Investigations
1st investigations to order
serum testosterone
Test
Used to exclude associated conditions.
High testosterone with high or normal follicle-stimulating hormone and luteinising hormone suggests partial androgen insensitivity syndrome.
Low testosterone and elevated gonadotrophins in males suggests Klinefelter's syndrome.
High androgens in females may suggest polycystic ovary syndrome.
Morning draw of the specimen is recommended.
Result
normal
serum dihydrotestosterone
Test
Routinely measured in some (but not all) centres. May be used to exclude associated conditions.
High testosterone and dihydrotestosterone with high or normal follicle-stimulating hormone and luteinising hormone suggests partial androgen insensitivity syndrome.
Morning draw of the specimen is recommended.
Result
normal
serum follicle-stimulating hormone (FSH) and luteinising hormone (LH)
Test
Used to exclude associated conditions.
High testosterone with high or normal FSH and LH suggests partial androgen insensitivity syndrome.
Low testosterone and elevated gonadotrophins in males suggest Klinefelter's syndrome.
Result
normal
serum prolactin
Test
Used to exclude associated conditions.
Elevation may suggest prolactinoma or drug use.
Post-treatment, prolactin should not rise above 1000 IU.
Should be repeated every 6 months while the patient is on hormonal therapy.
Result
normal
serum liver function tests
Test
Serum aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase should be followed up every 6 months while the patient is on hormonal therapy.
Result
normal baseline
serum lipid screen
Test
LDL-cholesterol may rarely rise with hormone treatment. Dyslipidaemia should be treated as it would be for any other cause.
Should be repeated every 6 months.
Result
should be normal initially
FBC
Test
Elevated mean corpuscular volume (MCV) denotes possible alcohol use disorder. Haemoglobin (Hb) may rise following androgen treatment, particularly in smokers.
Should be followed up every 6 months.
Result
MCV and Hb should be normal initially
Investigations to consider
serum prostate-specific antigen (PSA) in birth-assigned males
Test
In some locations, it is common practice to measure PSA in birth-assigned males at the age of 45 years and over prior to initiation of hormone therapy, in order to obtain a baseline level, and to rule-out undiagnosed prostate cancer.
Note that following the initiation of hormone treatment, PSA may be a less-useful measuring tool for prostate cancer, given that PSA levels ordinarily plummet in those taking gender-affirming hormone therapy; extra care is needed in interpreting results.[38]
Total PSA is the initial test of choice (i.e., the sum of both the free and bound forms).
Result
elevated PSA (value should be correlated with patient age and exposure to gender-affirming hormone treatment) indicates suspicion of prostate cancer
Serum 25-hydroxyvitamin D
Test
Vitamin D levels are routinely measured in some centres, given the high rate of vitamin D deficiency within the transgender population.[39]
25-hydroxyvitamin D is the major circulating form of vitamin D used to determine vitamin D status.[40]
Result
vitamin D deficiency: ≤50 nmol/L (≤20 ng/mL); vitamin D insufficiency: between 52-72 nmol/L (21-29 ng/mL)
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