2. Urine should ideally be refrigerated during collection. 3. Venous blood specimen is added to a heparinized or EDTA vial. Separate the cells from plasma immediately.

 

Normal Ranges

LH:mIU/mL FSH: mIU/mL PRL:(ng/mL)

Women: 1.2 – 15.5

Follicular phase 0.8 – 10.5 3.0 – 12.0

Midcycle 18.4 – 61.2 8.0 – 22.0

Luteal phase 0.8 – 10.5 2.0 – 12.0

Postmenopausal 8.2 – 40.8 35.0 – 151.0 1.5 – 18.5

Men 0.7 - 7.4 1.0 – 14.0 1.8 – 17

Sample Collection and Storage

LH and FSH

Plasma, serum or urine can be used for LH and FSH

measurements. Both hormones are stable for 8 days

at room temperature and for 2 weeks at 4°C; for longer

periods, the specimen should be stored frozen at or below

–20°C. Because of episodic, circadian and cyclic variations

in the secretion of gonadotrophins, a meaningful clinical

evaluation of these hormones may require determinations

in pooled blood specimens, multiple serial blood

specimens, or timed urine specimens (Fig. 24.22).

Prolactin

Serum is the specimen of choice for PRL assays and can

be stored at 4°C for 24 hours. Freezing is preferred for

maintaining long-term stability. Specimens should be

collected 3 to 4 hours after the patient has awakened,

since PRL levels rise rapidly during sleep and peak in early

morning hours. Emotional stress, exercise, ambulation,

and protein ingestion also elevate PRL levels. As PRL is

secreted episodically, multiple sampling techniques may

be advantageous (e.g. pooling equal volumes of sera from

specimens drawn at 6 to 18 min intervals).

The ranges will differ from laboratory to laboratory and

depend on the reference preparation used for the standards.

The range of values is plotted on a logarithmic scale.

Measured values differ significantly, depending on the

laboratory and immunoassay system employed (Fig. 24.23).

FIG. 24.21: Epitype characterization

FIG. 24.22: The ranges will differ from laboratory to laboratory and depends on the reference preparation used for the standards.

The dotted line represents the clinically important lower range

Schematic representation of the range of basal serum gonadotropin concentrations observed in various clinical states

774 Concise Book of Medical Laboratory Technology: Methods and Interpretations The dotted line signifies the upper limit of the normal

range in many laboratories.

Hyperprolactinemia

Hyperprolactinemia is defined as consistently elevated

Prolactin levels in the absence of pregnancy or postpartum

lactation and is considered as pituitary disorder.

Prolactin is a pituitary hormone that plays a role in a

variety of reproductive functions. It is essential for normal

production of breast milk following childbirth. Also, it

negatively modulates the secretion of pituitary hormones

responsible for gonadal function.

Causes for Hyperprolactinemia

Common causes: Pituitary tumors, usually prolactinomas,

which are under 10 mm in diameter.

Primary hypothyroidism, due to increased TRH

resulting in increased TSH and Prolactin.

Ingestion of certain drugs, including phenothiazine,

certain high blood pressure medicines (a-methyldopa),

tranquilizers and opioids, anti nausea drugs, oral

contraceptives.

Chronic kidney failure and other medical conditions.

Unexplained in about 30%.

Also associated with hypogonadotropinism and

hypogonadism.

Symptoms of Hyperprolactinemia

¾ Amenorrhea

¾ Oligomenorrhea

¾ Corpus luteum dysfunction

¾ Headaches and visual difficulties

¾ Loss of libido and sexual profency in men

¾ Lowered levels of LH and FSH

¾ Symptoms of estrogen deficiency (such as those of

menopause—hot flashes, dyspareunia), even in case of

normal estrogen production

¾ Signs of increased levels of androgens in women.

Diagnosis

Basal Prolactin level can adequately be used to gauge

pituitary tumor size and be followed over time.

Serum FSH, LH and estradiol—usually low to normal in

hyperprolactinemia.

¾ TSH to rule out hypothyroidism.

¾ CT or MRI to identify microadenomas.

¾ Visual-field examination—in case of macroadenomas

(>10 mm diameter) or any patient electing medical

therapy or surveillance only.

FIG. 24.23: The range of values is plotted on a logarthmic scale. Measured values differ significantly, depending on the laboratory and

immunoassay system employed. The dotted line signifies the upper limit of the normal range in many laboratories. The arrow signifies the

clinically important lower range

Schematic representation of the range of basal serum prolacting levels (ng/ml)

observed in various pathologic and pharmacologic states

The Endocrine System 775

Treatment

For patients >100 ng/mL of prolactin and normal CT/MRI

or patients with only microadenomas—Bromocriptine or

unmedicated surveillance.

Exogenous estrogen, in some cases, to combat low

estrogen levels.

ADRENAL CORTEX

The adrenal cortex produces four major groups of

hormones: (i) glucocorticoids (cortisol, cortisone), (ii)

androgens (androstenedione, dehydroepiandrosterone),

(iii) Mineralocorticoids (aldosterone, deoxycorticosterone,

corticosterone), and (iv) estrogens and progesterone.

Adrenal corticosteroid production is controlled by

a number of factors originating in the hypothalamicpituitary system. The ACTH is the major tropic substance

of the system. Aldosterone is under minimal control of

ACTH, and its secretion is mainly influenced by volume

receptors, angiotensin II and potassium concentration.

The plasma cortisol, in turn, regulates ACTH secretion.

The direct feedback mechanism does not seem operative

for aldosterone secretion.

Cortisol-binding globulin (CBG) avidly binds cortisol

and corticosterone and is the main carrier protein at

normal concentrations. Estrogens increase CBG are

inactive but are in equilibrium with free unbound steroid.

Actions

The mineralocorticoids increase reabsorption of sodium

and chloride, increased excretion of potassium, and

allow an exchange of intracellular potassium with

extracellular sodium. Aldosterone is most effective in this

regard. The glucocorticoids affect protein, carbohydrate,

and fat metabolism, raising blood glucose, increasing

gluconeogenesis and protein catabolism (with resulting

osteoporosis), metabolising hepatic fat depots, decreasing

tubular reabsorption of urates, increasing uropepsin

secretion, and lyzing eosinophils and lymphocytes.

Clinical Disorders of Adrenal Steroids

a. Deficiency

1. Acute: Addisonian crisis, Waterhouse-Friderichsen syndrome

2. Chronic: Addison’s disease.

b. Excess

1. Principal glucocorticoids: Cushing’s syndrome.

2. Principal androgen excess: Adrenogenital syndrome in females, macrogenitosomia in males.

3. Aldosterone excess: Primary hyperaldosteronism.

Methods of Evaluation of Glucocorticoids and

Androgens

Evaluation of adrenocortical function may depend upon:

(i) physical examination, noting particularly pigmentation

of the skin and mucous membranes, pubic and axillary

hair growth, blood pressure and the presence of edema,

(ii) determination of serum sodium, potassium, chloride,

CO2, urea and protein, (iii) X-ray studies of the bones for

osteoporosis and of the adrenal region, with or without

retroperitoneal pneumography and tomography, (iv)

determination of blood and urine levels of 17-ketosteroids,

17-hydroxycorticosteroids, aldosterone and specific excretory products such as androsterone and etiocholanolone,

pregnanetriol, and pregnenetriolone, (v) specific function

tests such as the water loading test and the response of

hormone excretion levels to stimulation by exogenous

ACTH, inhibition of ACTH production by corticosteroids,

or inhibition of 11-β hydroxylation by metyrapone; and

(vi) in the absence of interfering factors, the number of

circulating eosinophils, normally between 100 and 300/ml,

varying inversely with adrenocortical activity.

Urinary 17-Hydroxycorticosteroids, 17-Ketosteroid

Excretion, Ketogenic Steroids, or Free Cortisol

The basal 24 hours urine excretion of 17-hydroxycorticosteroids is the most frequently used test in assessing

adrenocortical activity. Paraldehyde, quinine, colchicine,

iodides, sulfamerazine, and chlorpromazine interfere with

the Porter-Silber steroid determination. The 17-hydroxycorticosteroids are metabolites of cortisol and cortisone.

Urinary 17-ketosteroids are metabolites of: (i) adrenocortical steroids such as cortisol, (ii) adrenal androgens,

and (iii) gonadal androgens.

The test, hence, reflects the activity of the adrenal

cortex and the gonads in the male and the adrenal cortex

in the female. There is a diurnal variation in excretion of

17-hydroxycorticosteroids and 17-ketosteroids of adrenal

origin. The contribution of testosterone metabolites to the

ketosteroids in the urine is minimal.

The 17-ketosteroid levels determined by the Zimmermann reaction are greatly reduced by probenecid and

meprobamate administration. These drugs should be

stopped for several days before urine collection.

The patient should not be receiving androgens or cortisol

when specimens are collected. Testosterone propionate is

excreted in the urine and is measured as 17-ketosteroids,

methyltestosterone does not appear in the urine.

776 Concise Book of Medical Laboratory Technology: Methods and Interpretations Method

A 24 hours urine specimen is collected in a jug containing

5 mL of 2% thymol glacial acetic acid.

Interpretation

High levels of excretion of both 17-hydroxycorticosteroids,

17-ketosteroids, ketogenic steroids, and urinary-free

cortisol are found in adrenocortical carcinoma and

adrenocortical hyperplasia, and of 17-ketosteroids and

pregnanetriol in the adrenogenital syndrome. Low levels

of excretion are found in hypopituitarism. Addison’s

disease, myxedema, and occasionally in anorexia nervosa.

Aldosterone

Aldosterone, Serum and Urine

Normal values

Average-Sodium diet Serum SI units

Peripheral blood

 Supine 3–10 ng/dL 0.14–1.9 nmol/L

 Upright

 Adult female

 pregnant 18–100 ng/dL 0.5–2.8 nmol/L

 Nonpregnant 5–30 ng/dL 0.14–0.8 nmol/L

 Adult male 6–22 ng/dL 0.17–0.61 nmol/L

Adrenal vein

Child

 1 week–12 months 1–60 ng/dL 0.03–4.43 nmol/L

 Age 1–3 years 5–60 ng/dL 0.14–1.7 nmol/L

 Age 3–11 years 5–70 ng/dL 0.14–1.9 nmol/L

 Age 11–15 years <5–50 ng/dL <0.14–1.4 nmol/L

Urinary aldosterone

Norm urine 2–26 mg/24 h 5.6–73 nmol/day

Urinary sodium Plasma renin µg/day nmol/day

<30 nmol/day 5–24 Al/mL/h 35–80 97–220

20–50 nmol/day 2–7 Al/mL/h 13–33 36–91

50–100 nmol/day 1–5 Al/mL/h 5–24 14–66

100–150 nmol/day 0.5–4 Al/mL/h 3–19 8–53

150–200 nmol/day 1–16 3–44

200–250 nmol/day 1–13 3–36

This cholesterol-derived hormone is the most potent

of the mineralocorticoids. Its foremost physiologic

effect is that of regulating the transport of ions across

cell membranes, especially those of renal tubules. This

hormone causes the retention of sodium and chloride and

the elimination of potassium and hydrogen. The second

is the maintenance of blood pressure. Minute quantities

will depress the urinary and salivary sodium to potassium

ratio primarily because of diminished sodium excretion.

The three main factors that apparently affect aldosterone

levels include the renin-angiotensin system, the plasmapotassium concentration and ACTH. The renin-angiotensin

system appears to be the major mechanism that controls

extracellular fluid by regulation of aldosterone secretion.

Potassium loading results in increased aldosterone levels,

whereas a potassium-deficient diet in the presence of

aldosterone excess will result in a lowered aldosterone level.

Increased concentrations of potassium in the blood plasma

directly stimulate adrenal production of the hormone. The

ACTH may affect aldosterone production in conditions

of acute stress, burns, hemorrhage, and other pathologic

conditions. Under physiologic conditions, ACTH seems to

have little effect on aldosterone production.

Method

1. A 24 hours urine specimen is obtained.

2. Urine should ideally be refrigerated during collection.

3. Venous blood specimen is added to a heparinized or

EDTA vial. Separate the cells from plasma immediately.

Specimen should be obtained in the morning after the

patient has been upright for at least 2 hours.

4. Specify and record the source of the specimen (e.g.

peripheral venous, etc.).

Diuretic agents, progestational agents, estrogens, and

liquorice should be discontinued 2 weeks prior to test. The

patient’s diet for 2 weeks before the test should be normal

and include 3 gm of sodium per day.