On the other hand the circulatory insulin can be found at much higher levels like in patients with pancreatic tumors. These tumors secrete abnormally high levels of insulin and

 

The cost benefits should be considered in the use

of thyroglobulin antibodies testing when performed

in concent with antithyroid peroxidase (TPO). The

widespread practice of performing both tests has been

questioned.

Expected Range of Values

Expected values for the anti-Tg ELISA test system

(in IU/mL)

Upper 95% (+2*) level 124.7

Thyroid Peroxidase Antibodies

Interpretation

The presence of autoantibodies to TPO is confirmed when

the serum level exceeds 40 IU/mL. The clinical significance

of the result, coupled with antithyroglobulin activity, should

be used in evaluating the thyroid condition. However,

clinical inferences should not be solely based on this test

but rather as an adjunct to the clinical manifestations of the

patient and other relevant tests.

Expected Range of Values

Expected values for the anti-TPO ELISA test system

(in IU/mL)

Upper 95% (+2a) level 39.2

Luteinizing Hormone (LH)

Interpretation

LH is suppressed by estrogen; but in women taking oral

contraceptives, the level may be low or normal. Excessive

dieting and weight loss may lead to low gonadotropin

concentrations.

Luteinizing hormone is dependent upon diverse factors

other than pituitary homeostasis. Thus, the-determination

alone is not sufficient to assess clinical status.

Expected Range of Values

Expected values for the LH IEMA test system

(in mlU/mL) (IRP 68/40)

Women Follicular phase 0.8–10.5

Midcycle 18.4–61.2

Luteal phase 0.8–10.5

Postmenopausal 8.2–40.8

Men 0.7–7.4

Usage

To evaluate infertility in women and men (high serum

values are related to gonadal dysfunction, and low

values of LH are related to dysfunction or failure of the

hypothalamus or pituitary gland) to evaluate hormonal

therapy for inducing ovulation and to evaluate endocrine

problems related to precocious puberty in children. The

results of LH assay are shown in Figure 24.24.

Values are Increased in

Amenorrhea, endocrine, problems related to precocious

puberty in children, hyperpituitarism, Klinefelter’s

syndrome, liver disease, menopause, menstruation,

ovarian or testicular failure (primary gonadal dysfunction)

Stein-Levinthal syndrome (polycystic ovarian disease),

tumor (pituitary, testicular), and Turner’s syndrome

(ovarian dysgenesis). Drugs includeanticonvulsants,

clomiphene, naloxone, and spironolactone.

786 Concise Book of Medical Laboratory Technology: Methods and Interpretations Values are Decreased in

Adrenal hyperplasia or tumor, amenorrhea, (pituitary

failure, secondary gonadal insufficiency), anorexia

nervosa, anovulation, hypophysectomy, hypopituitarism,

hypothalamic disorder, malnutrition, pituitary disorder,

and testicular failure (related to pituitary failure). Drugs

include digoxin, estrogen compounds, oral contraceptives,

phenothiazines, progesterone, stanozlol, and testosterone

administration.

Follicle Stimulating Hormone (FSH)

Interpretation

The FSH is suppressed by estrogen, but in women taking

oral contraceptives, the level may be low or normal.

Excessive dieting and weight loss may lead to low

gonadotropin concentrations.

Follicle-stimulating hormone is dependent upon

diverse factors other than pituitary homeostasis. Thus, the

determination alone is not sufficient to assess clinical status.

Normal Values in mIU/mL

Sex/phase

Males 1.0–14.0

Females:

Follicular phase 3.0–12.0

Midcycle 8.0–22.0

Luteal phase 2.0–12.0

On oral contraceptives Up to 3.0

Postmenopausal 35.0–151.0

Values are Increased in

Acromegaly (early), amenorrhea (primary), anorchism, castration, gonadal failure, hyperpituitarism,

hypogonadism, hypothalamic tumor, hysterectomy,

Klinefelter’s ovarian failure, pituitary tumors, precocious

puberty, premature menopause, seminiferous

tubule failure, seminoma, Stein-Levinthal syndrome

(polycystic ovary syndrome), testicular agenesis,

testicular destruction (due to radiation or mumps

FIG. 24.24: Ultrasensitive TSH assay

The Endocrine System 787

orchitis), testicular failure, testicular feminization

syndrome (complete), and Turner’s syndrome (primary

hypogonadism).

Values are Decreased in

Adrenal hyperplasia, amenorrhea (secondary), anorexia

nervosa, anovulatory menstrual cycle, delayed puberty,

hypogonadotropism, hypophysectomy, hypothalamic

dysfunction, neoplasm (adrenal, ovarian, testicular),

panhypopituitarism, and prepubertal child. Drugs

include chlorpromazine, estrogens, oral contraceptives,

progesterone, and testosterone.

Prolactin Hormone (PRL)

Interpretation

Patient specimens with abnormally high prolactin

levels can cause a hook effect, that is, paradoxical

low absorbance results. If this is suspected, dilute the

specimen 1/100 with 0 calibrator, reassay (multiply the

result by 100). However, values as high as 3000 ng/mL

have been found to absorb greater than the absorbance

of the highest calibrator.

Patients receiving preparations of mouse monoclonal

antibodies for diagnosis or therapy may contain human

antimouse antibodies (HAMA) and may show either

falsely elevated or depressed values when assayed.

Pregnancy, lactation, and the administration of oral

contraceptives can cause an increase in the level of prolactin.

Drugs such as morphine, reserpine and the psychotropic

drugs and domperidone, etc. increase prolactin secretion.

Since prolactin hormone concentration is dependent

upon diverse factors other than pituitary homeostasis, the

determination alone is not sufficient to assess clinical status.

Expected Range of Values

Normal range of HPRL in ng/mL

Age/sex/phase

Newborn > 250

Adult male < 20

Adult female, nonlactating < 25

Follicular phase < 28

Luteal phase 5–40

Postmenopausal < 12

Pregnancy

Trimester 1 < 80

Trimester 2 < 160

Trimester 3 < 400

Pituitary tumor > 100

HPRL Levels are Increased in

Acromegaly, Addison’s disease, amenorrhea, anorexia

nervosa, breast stimulation, bronchogenic carcinoma,

Chiari-Frommel syndrome, coitus, Del Castillo’s

syndrome, ectopic tumors, endometriosis, exercise.

Forbes-Albright syndrome, galactorrhea, hyperestrogen states, hyperpituitarism, hypothalamic disorders,

hypothyroidism (primary), hysterectomy, idiopathic causes

(e.g. early micro-adenoma that are undetectable by radiology), impotence, lactation, Nelson’s syndrome, neurogenic

causes, pituitary tumors, polycystic ovaries, pregnancy.

Chronic renal failure, sleep and stress, drugs include

amitryptiline, amoxapine, amphetamines, benzamides,

chlorprothixine, desipramine, doxepin, droperidol,

estrogens, haloperidol, imipramine, isoniazid, maprotiline,

meprobamate, methyldopa, metoclopramide, nortripty -

line, opiates, oral contraceptives, phenothiazines, procainamide hydrochloride, protriptyline, reserpine, thioridazine,

thiothixene, thyrotropin, triavli, and trimipramine maleate

and gastric intestinal prolinetic drugs.

HPRL Levels are Decreased in

Gynecomastia, hirsutism, osteoporosis, and pituitary

necrosis/infarction. Drugs include apomorphine hydrochloride, clonidine, bromocripine mesylate, dihydroergotamine, mesylate, dopamine, ergonovine maleate, ergotamine tartarate, ergoloid mesylate, lergotrile, levodopa,

and lisuride hydrogen maleate.

Human Chorionic Gonadotropin (hCG)

Interpretation

False positive results may occur in the presence of a wide

variety of trophoblastic and nontrophoblastic tumors that

secrete hCG. Therefore, the possibility of an hCG secreting

neoplasia should be eliminated prior to diagnosing

pregnancy.

Also, false positive results may be seen when assaying

specimens from individuals taking the drugs Pergonal and

Clomid. Additionally, Pergonal will often be followed with

an injection of hCG.

Spontaneous microabortions and ectopic pregnancies

will tend to have values which are lower than expected

during a normal pregnancy, while somewhat higher values

are often seen in multiple pregnancies.

Following therapeutic abortion, detectable hCG may

persist for as long as 3 to 4 weeks. The disappearance rate

of hCG, after spontaneous abortion, will vary depending

upon the quantity of viable residual trophoblast.

788 Concise Book of Medical Laboratory Technology: Methods and Interpretations Normal Values in mIU/mL

Males < 5.0

Females:

Nonpregnant < 20.0

< 1 week gestation Up to 50.0

2 weeks gestation 50–500

3 weeks gestation 100–10,000

4 weeks gestation 1000–30,000

5 weeks gestation 3,500–115,000

6-8 weeks gestation 12,000–270,000

12 weeks gestation 15,000–220,000

Values are Increased in

Choriocarcinoma, eclampsia, ectopic pregnancy, erythroblastosis fetalis, germ cell tumors, gynecomastia,

hydatidiform mole, insulinoma, neoplasms (colon, lung,

pancreas, stomach), ovarian cancer, pregnancy, seminoma,

and testicular cancers and possibly bladder cancer.

Values are Decreased in Abortion and

Ectopic Pregnancy

The hCG testing may help differentiate actual pregnancy

from an ectopic pregnancy in conjunction with an

ultrasound.

Avoid medications such as anticonvulsants, antiparkinsonism agents, hypnotics, tranquilizers, which may

cause a false positive result.

Factors that Affect Results

¾ False positive results may be due to incorrect handling

of the test sample, excessive production of luteinizing

hormone (LH) of the pituitary gland, absence of

gonadal hormones in menopausal women or hCG

producing tumors

¾ False negative results may be due to the test being

performed too early in pregnancy.

Other Data

Although not usually present in healthy males or

nonpregnancy females, elevated levels of hCG may be

detected in patients with certain malignant tumors.

CIA™ INSULIN

(Chemiluminescence Immunoassay)

(Courtesy: Lilac Medicare)

Insulin Microplate CIA

Intended Use: Monobind insulin microplate CIA test is

intended to be used for the quantitative determination

of insulin levels in human serum. The test is for in vitro

diagnostic use only.

Summary and Explanation of the Test

Human insulin is a peptide produced in the beta cells of the

pancreas and is responsible for the metabolism and storage

of carbohydrates. As a result of biofeedback the insulin

levels increase with intake of sugars and decline when sugar

content is low for absorption. In the diabetic population

the mechanism of insulin production is impaired because

of genetic predispositions (Type I) or because of lifestyle

and/or hereditary factors (Type II). In such cases either the

insulin production has to be boosted by medication or it

has to be supplemented by oral or intravenous methods.

The quantitative determination of insulin can help in dose

selection the patient has to be subjected to.

On the other hand the circulatory insulin can be found at

much higher levels like in patients with pancreatic tumors.

These tumors secrete abnormally high levels of insulin and

thus cause hypoglycemia. Accordingly, fasting hypoglycemia associated with inappropriately high concentrations

of insulin strongly suggests an islet-cell tumor (insulinoma).

To distinguish insulinomas from factitious hypoglycemia

due to insulin administration, serum C-peptide values

are recommended. These insulinomas can be localized

by provocative intravenous doses of tolbutamide and

calcium.