Case File Hyperprolactinemia

8/11/2019 Case File Hyperprolactinemia

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Case File


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Case # 14

A 30-year-old parous woman notes a watery breast

discharge of 6 months duration. Her menses havebeen somewhat irregular. She denies a family history

of breast cancer. The patient had been treated

previously with radioactive iodine for Graves disease.

Currently, she is not taking any medications. Onexamination, she appears alert and in good health. The

blood pressure (BP) is 120/80 mm Hg, and heart rate

(HR) is 80 beats per minute (bpm). The breasts are

symmetric and without masses. No skin retraction is

noted. A white discharge can be expressed from both

breasts. No adenopathy is appreciated. The pregnancy

test is negative.


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Our Approach to patient

What is the most likely diagnosis? What is your next step?

What is the likely mechanism for this

disorder?


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Summary:

A 30-year-old parous woman withirregular menses notes a watery

breast discharge of 6 months

duration. She had been treatedpreviously with radioactive iodine for

Graves disease. The pregnancy test

is negative.


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Most likely diagnosis:.

Next step:

Likely mechanism:

Most likely diagnosis:. Galactorrhea due to

hypothyroidismNext step: Check serum prolactin

and TSH levels.

Likely mechanism: Hypothyroidism is associated with anelevated thyroid releasing hormone

(TRH) level, which acts as a prolactin-

releasing hormone.

The hyperprolactinemia then induces

the galactorrhea.


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Hyperprolactinemia

Levels of circulatingprolactin above normal(>20 to 25 ng/mL) that can cause

galactorrhea or amenorrhea or both.

The optimal time to obtain a blood sample

for assay to diagnose is during the

midmorning hours.

Reference range

Female - gravid/nonlactatin : 2-29 ng/ml Gravid : 10-29 ng/ml

Male : 2-18 ng/ml


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Prolactin

Polypeptide hormone Contains 198 amino acids

MW of 22,000 daltons.

Different molecular sizes: Monomeric(small): 22,000 daltons

Polymeric(big): 50,000 daltons

Larger polymeric(big-big): > 100,000 daltons


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FORMS

1. Larger forms - contain added sugar moieties

(glycosylation) which decreases biologic

activity.

2. Small form(80%) - biologically active

3. Polymeric forms - have reduced biologic

activity and reduced binding to mammary

tissue membranes.

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Synthesized and stored in the pituitary gland

in chromophobe cells (lactotrophs),which arelocated mainly in the lateral areas of the gland

Encoded by its gene (10 kb) on chromosome 6

Prolactin9


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At the molecular level, it is stimulated and

suppressed by multiple factors.

Thyroid-releasing hormone(TRH) - Principal

stimulating factor

Dopamine- Major inhibiting factor

Estrogen - Enhances the effects of TRH and

inhibits the effects of dopamine

Galanin - May also mediate a potential direct effect

Prolactin10


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In addition, PRL is synthesized in decidualized

stroma of endometrial tissue.

From these tissues PRL is secreted into the

circulation and, in the event of pregnancy, intothe amniotic fluid.

The control of decidual PRL is different from

that of the pituitary and does not respond to

dopamine.

Prolactin11


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Normally present in measurable amounts in

serum

Mean levels of about 8 ng/mL in adult women

Circulates in an unbound form

20-minute half-life

Cleared by the liverand kidneys

Prolactin12


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Main function is to stimulate the growth of

mammary tissue as well as to produce andsecrete milk into the alveoli(mammogenic and

lactogenic).

Specific receptors for PRL are present in the

plasma membrane of mammary cells as well

as many other tissues

Prolactin13


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Case File Hyperprolactinemia

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