The Endocrine System

Different hormones, different signals Anterior pituitary Thyroid gland TSH Thyroid hormones Negative feedback - + Hypo- thalamus Water absorption ADH osmolality Negative feedback - + Pancreas Liver, fat & muscle Insulin Glucose Negative feedback - + Para- thyroids Bone, GIT & Kidney PTH calcium Negative feedback - +

Growth Hormone Release of GH is stimulated by the release of GHRF secreted by the hypothalamus GH is inhibited by –Glucocorticoids –Obesity –Depression –Progesterone –Hypokalemia –Altered thyroid function

Hormones of pituitary gland

Deficit of GH

Overproduction of GH

Posterior pituitary hormones

Synthetic Human Growth Hormones somatrem (Protropin) somatropin (Humatrope) Drug List

Growth Hormone The younger the patient at time of treatment the greater the height that may be achieved Little response is seen after age in boys and in girls

Thyroid Gland Produces hormones (T 3 and T 4 ) that stimulate metabolic activity of body tissues Hypothalamus and pituitary glands work together to release TSH TSH stimulates T 3 and T 4 release

Thyroid Hormone Feedback Loop Thyroid hormones build up in the blood Signals are sent to the hypothalamic- pituitary axis that adequate levels have been met TSH levels decrease

Feedback Anterior pituitary Thyroid gland TSH Thyroid hormones Negative feedback - +

Hypothyroidism Production of thyroid hormones is below normal Cretinism occurs in children at birth due to inadequate maternal iodine intake –Can cause mental retardation, thick tongue, lethargy, lack of response, short stature – can be corrected if treated

Primary and secondary disorders Primary Thyroid disease Secondary Thyroid disease

Hypothyroidism Symptoms Apathy Constipation Decreased heart rate Depression Dry skin, nails, and scalp Easy fatiguing Enlarged thyroid Lowered voice pitch Myxedema Puffy face Reduced mental acuity Swelling of eyelids Tongue enlarged and thickened Weight gain

Struma (goiter) and hyperthyroidism Hypothyroidism Thyrotoxicosis Thyrotoxicosis

Congenital hypothyroidism (physical and mental retardation – nanism - pygmy, idiotism

Causes of Hypothyroidism Autoimmune destruction of the gland Radioactive iodine therapy Surgical removal of the gland

Agents for Hypothyroidism levothyroxine, T 4 (Levothroid, Levoxyl, Synthroid) liothyronine, T 3 (Cytomel) liotrix (Thyrolar) thyroid (Armour Thyroid) Drug List

levothyroxine, T 4 (Levothroid, Levoxyl, Synthroid) Used for chronic therapy Can be cardiotoxic Alters protein binding of other drugs Should not switch brands once stabilized

levothyroxine Dispensing Issues Can be cardiotoxic; report any of the following: –Chest pain, increased pulse, palpitations, heat intolerance, excessive sweating Warning!

levothyroxine Dispensing Issues Look-alike and Sound-alike Drugs: –levothyroxine (thyroid replacement) –levofloxacin (antibiotic) Warning!

Hyperthyroidism Excessive thyroid hormone Most common cause is Grave’s disease Other causes: –Excessive exogenous iodine –Thyroid nodules –Tumor in the pituitary causing overproduction of TSH

Symptoms of Hypterthyroidism Decreased menses Diarrhea Exophthalmos Flushing of the skin Heat intolerance Nervousness Perspiration Tachycardia Weight loss

Agents for Hyperthyroidism methimazole (Tapazole) propylthiouracil, PTU radioactive iodine, 131 I Drug List

Hypoglycemic Agents In the islets of Langerhans, in the pancreas, there are two primary specialized cells Alpha Cells –Produce glucagon and raise blood glucose levels Beta Cells

Hypoglycemic Agents In the islets of Langerhans, in the pancreas, there are two primary specialized cells Alpha Cells –Produce glucagon and raise blood glucose levels Beta Cells –Produce insulin and lower blood glucose levels

Insulin Helps cells burn glucose for energy Works with receptors for glucose uptake Enhances transport and incorporation of amino acids into protein Increases ion transport into tissues Inhibits fat breakdown

Insulin Administered subcutaneously due to degradation in the GI tract Different types of insulin have different onset of action times and duration of action times

Insulin Duration of Action TypeDuration of Action Humalog, Novolog 1 hr (works in 15 mins and gone in about an hour) Regular5-6 hours (onset – 30 mins) NPH10-16 hours Lente12-18 hours Lantus24 hours mixedQuick onset, longer duration

Insulin Dispensing Issues It is very easy to grab the wrong insulin in the refrigerator Always double-check yourself They look exactly alike Warning!

Insulin administration sites should be rotated

Hypoglycemia Blood glucose levels of <70 mg/dL Can be caused by –Skipping meals –Too much exercise –Poor medication regimen –Certain drugs

Signs & Symptoms of Hypoglycemia Confusion Double vision Headache Hunger Numbness and tingling in mouth and lips Nervousness Palpitations Sweating Thirst Visual disturbances Weakness

insulin glargine (Lantus) Synthetic long-acting insulin Absorbed slowly and works over a 24-hour time period Works similarly to physiologic insulin release

Human Insulins Mixtures insulin aspart w/ protamine-insulin aspart (NovoLog Mix 70/30) insulin lispro w/ protamine-insulin lispro (Humalog Mix 75/25) insulin with zinc (lente) (Humulin L) NPH-regular insulin (Humulin 70/30) Drug List

Oral Hypoglycemic Agents First- Generation Sulfonylureas chlorpropamide (Diabinese) tolbutamide Drug List

Oral Hypoglycemic Agents Second-Generation Sulfonylureas glimepiride (Amaryl) glipizide (Glucotrol, Glucotrol XL) glyburide (DiaBeta, Glynase, Micronase) Drug List

Oral Hypoglycemic Agents Enzyme inhibitors: acarbose (Precose) miglitol (Glyset) Biguanide: metformin (Glucophage, Riomet) Drug List

Oral Hypoglycemic Agents Combinations glipizide-metformin (Metaglip) glyburide-metformin (Glucovance) rosiglitazone-metformin (Avandamet) Drug List