Endocrinology: connect hormones, feedback and target tissues
Endocrinology examines hormones and the glands and tissues involved in their production and responsiveness to them. Hormone results make more sense when they fit into a signaling pathway. Begin with the source (where the hormone comes from), target (the specific area or organ that will have a reaction) and response (what will happen due to the hormone's presence).
A circulating signal needs a responding tissue
Endocrine signals circulate throughout the body and act on tissues that are responsive to the signal. The location of a hormone's origin and the location of a reacting tissue can be different. The presence of a hormone alone does not provide all of the necessary information to understand the full reaction; the target’s ability to recognise and respond also matters.
Draw a pathway. Name each part of the pathway individually (gland, hormone and target). Write down the effect last. Do this so that a list of gland names is not confused for an explanation of how a hormone signals. Also, draw parallels between endocrinology and physiology and pharmacology. Draw parallels between what a laboratory test is investigating and the actual processes happening within the body.
Follow the loop rather than a single isolated arrow
Many endocrine systems utilize some form of negative feedback. Feedback mechanisms allow endocrine systems to coordinate and communicate through multiple components. As such, changes in measured concentrations can represent responses outside of the original sampled gland. For revision purposes, define each portion of your arrows in words: What stimulated what? What altered the signal?
Do not assume that an increase in concentration equates to increased overall physiological effect. Do not assume that one result identifies the cause of an abnormal value. Relevant interpretations depend upon the specific hormone system investigated, relevant additional findings and the specific sampling circumstance.
Different endocrine conditions involve different kinds of disturbance
Thyroid hormones influence energy use and affect many tissues. There is a difference between having insufficient thyroid hormone and excess levels. Blood glucose regulation in people with diabetes is disrupted either by problems related to insulin production, insulin action or both based on type. Examples above demonstrate why endocrine disease should be explained through understanding the unique pathway that is affected.
Compare examples by naming the signal (hormone), the regulated process (physiological event/process) and what evidence indicates the degree of regulated process disruption. Many symptoms (e.g., fatigue or weight gain/loss) can indicate many causes, but these symptoms alone do not narrow an endocrine diagnosis. The example establishes a mechanism for what happened; it does not establish if that mechanism occurred in a given person.
Interpret the result before choosing an explanation
Laboratory testing assessing hormonal levels requires consideration of time (when did the blood sample occur?), other tested hormones, medications taken and pre-existing medical conditions. Not every investigation measures only one resting level. The clinical question dictates which method(s) to use. A laboratory flag calls for interpretation; it does not include directions for treatment next to the numerical result.
Treatments can replace absent hormones, decrease excessive amounts of hormones, or address another part of a condition. These are different objectives for treatments, and individuals require ongoing monitoring for each objective. Individuals should not start, stop or change doses of hormone medicines using general study guides. For revision purposes, outline the intended goal of treatment, allowing individual selections and dosages to remain under the responsibility of the appropriate healthcare professionals.
Check your understanding
A short quiz, with an explanation after each answer.
What is needed for a tissue to respond to a hormone?
Go back to the most difficult topic you identified and explain the example provided without reviewing the webpage. Review your explanation, then take the quiz again later. To be able to think out a rationale regarding what you learned is far better than simply memorizing where answers appear.