Prolactinoma laboratory tests: Difference between revisions
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==Overview== | ==Overview== | ||
Laboratory findings consistent with the diagnosis of prolactinoma include markedly elevated [[prolactin]] levels. | Laboratory findings consistent with the diagnosis of [[prolactinoma]] include markedly elevated [[prolactin]] levels. | ||
==Laboratory Findings== | ==Laboratory Findings== | ||
*Prolactin levels - Serum prolactin concentration may be markedly higher than normal (usually >200ng/ml). | *'''Prolactin levels''' - Serum [[prolactin]] concentration may be markedly higher than normal (usually >200ng/ml). | ||
*TSH levels - Thyrotropin releasing hormone(TRH) also stimulated prolactin secretion. Thyroid stimulating hormone(TSH) is measured. If TSH is elevated, free thyroxine (T4) level must be done to confirm that TSH elevation is due to elevated TRH and not due to decreased T4(hypothyroidism). | *'''TSH levels''' - [[Thyrotropin-releasing hormone|Thyrotropin releasing hormone]]([[Thyrotropin-releasing hormone|TRH]]) also stimulated prolactin secretion. [[Thyroid-stimulating hormone|Thyroid stimulating hormone]]([[Thyroid-stimulating hormone|TSH]]) is measured. If [[Thyroid-stimulating hormone|TSH]] is elevated, free [[thyroxine]] ([[T4]]) level must be done to confirm that [[Thyroid-stimulating hormone|TSH]] elevation is due to elevated [[Thyrotropin-releasing hormone|TRH]] and not due to decreased [[Thyroxine|T4]]([[hypothyroidism]]). | ||
*Pregnancy test | *'''Pregnancy test''' - [[Pregnancy test|Urine pregnancy test]](beta-hcg) is performed as [[pregnancy]] causes physiologic rise is [[prolactin]] levels. | ||
*Serum testosterone levels | *'''Serum testosterone levels''' - Low levels of serum [[testosterone]] are found in male presenting with symptoms of [[hypogonadism]]. | ||
*IGF-1 | *'''IGF-1''' - [[Insulin-like growth factor-1]] levels may be done in patients with features suggestive of [[acromegaly]]. | ||
*Cortisol levels | *Cortisol levels - Cortisol levels may be done in patients with features suggestive of Cushing's syndrome. | ||
*LFT | *'''LFT''' - Liver function tests may be done in patients with appropriate history to exclude cirrhosis or viral hepatitis as cause of elevated prolactin. | ||
*RFT | *'''RFT''' - Renal function tests may be done in patients with appropriate history to exclude chronic renal failure as cause of elevated prolactin. | ||
====Hook effect==== | ====Hook effect==== | ||
*Hook effect is a phenomenon which occurs particularly in macroprolactinoma.<ref name="pmid8729527">{{cite journal| author=St-Jean E, Blain F, Comtois R| title=High prolactin levels may be missed by immunoradiometric assay in patients with macroprolactinomas. | journal=Clin Endocrinol (Oxf) | year= 1996 | volume= 44 | issue= 3 | pages= 305-9 | pmid=8729527 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8729527 }} </ref> | *Hook effect is a phenomenon which occurs particularly in macroprolactinoma.<ref name="pmid8729527">{{cite journal| author=St-Jean E, Blain F, Comtois R| title=High prolactin levels may be missed by immunoradiometric assay in patients with macroprolactinomas. | journal=Clin Endocrinol (Oxf) | year= 1996 | volume= 44 | issue= 3 | pages= 305-9 | pmid=8729527 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8729527 }} </ref> | ||
*In patients with macroprolactinoma, the reading of initial prolactin level may be mistakenly normal or mildly increased. | *In patients with macroprolactinoma, the reading of initial [[prolactin]] level may be mistakenly normal or mildly increased. | ||
*These false values are due large amount of antigens. So, this is also called as 'high dose hook effect'. | *These false values are due large amount of [[Antigen|antigens]]. So, this is also called as 'high dose hook effect'. | ||
*All patients of pituitary macroadenomas shall underogo immunoradiometric prolactin assay with multiple dilution if prolactinoma is suspected. | *All patients of [[pituitary]] macroadenomas shall underogo immunoradiometric [[prolactin]] assay with multiple dilution if [[prolactinoma]] is suspected. | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: , Anmol Pitliya, M.B.B.S. M.D.[2], Faizan Sheraz, M.D. [3]
Overview
Laboratory findings consistent with the diagnosis of prolactinoma include markedly elevated prolactin levels.
Laboratory Findings
- Prolactin levels - Serum prolactin concentration may be markedly higher than normal (usually >200ng/ml).
- TSH levels - Thyrotropin releasing hormone(TRH) also stimulated prolactin secretion. Thyroid stimulating hormone(TSH) is measured. If TSH is elevated, free thyroxine (T4) level must be done to confirm that TSH elevation is due to elevated TRH and not due to decreased T4(hypothyroidism).
- Pregnancy test - Urine pregnancy test(beta-hcg) is performed as pregnancy causes physiologic rise is prolactin levels.
- Serum testosterone levels - Low levels of serum testosterone are found in male presenting with symptoms of hypogonadism.
- IGF-1 - Insulin-like growth factor-1 levels may be done in patients with features suggestive of acromegaly.
- Cortisol levels - Cortisol levels may be done in patients with features suggestive of Cushing's syndrome.
- LFT - Liver function tests may be done in patients with appropriate history to exclude cirrhosis or viral hepatitis as cause of elevated prolactin.
- RFT - Renal function tests may be done in patients with appropriate history to exclude chronic renal failure as cause of elevated prolactin.
Hook effect
- Hook effect is a phenomenon which occurs particularly in macroprolactinoma.[1]
- In patients with macroprolactinoma, the reading of initial prolactin level may be mistakenly normal or mildly increased.
- These false values are due large amount of antigens. So, this is also called as 'high dose hook effect'.
- All patients of pituitary macroadenomas shall underogo immunoradiometric prolactin assay with multiple dilution if prolactinoma is suspected.
References
- ↑ St-Jean E, Blain F, Comtois R (1996). "High prolactin levels may be missed by immunoradiometric assay in patients with macroprolactinomas". Clin Endocrinol (Oxf). 44 (3): 305–9. PMID 8729527.