2nd order laboratory parameters – depending on the results of the medical history, physical examination, etc. – for differential diagnostic clarification
- FSH [Klinefelter syndrome: ↑↑↑]
- LH [Klinefelter syndrome: elevated LH levels correlate with decreased testosterone; however, these often remained elevated even after testosterone levels normalized]
- Somatotropic hormone (STH) (synonyms: somatotropin; English somatotropic hormone; HGH or hGH (human growth hormone), GH (growth hormone), growth hormone) – in suspected acromegaly [serum GH ↑; the GH concentration is usually basally elevated; however, since GH is secreted episodically, the significance of a single value is very limited]
- Serum IGF-I (insulin-like growth factor-I; somatomedin) – if acromegaly is suspected [serum IGF-I: ↑]
- Thyroid parameters – TSH, fT3, fT4.
- Testosterone (determination in the morning) [Klinefelter syndrome: normal or ↓]
- Chromosome analysis (karyotype determination) – if Klinefelter syndrome is suspected.
