PHYSIOLOGY

Explain why so few cases of cretinism are seen today?

 

Cretinism, also known as congenital hypothyroidism, is a condition caused by a deficiency of thyroid hormones while a fetus is developing in the womb or shortly after birth. In developing countries, the cause is usually a lack of iodine, but in developed countries, this deficiency is usually caused by a defect in the development of the thyroid gland itself, though it has also been linked to an inherited condition that interrupts the synthesis of thyroxine. Thyroxine is a hormone comprised primarily of iodine that regulates the rate of cellular oxidation. Another cause has been attributed to antithyroid medications taken by the mother during pregnancy, but this cause is infrequent.

Left untreated, cretinism can stunt growth to the degree of dwarfism and causes severe mental retardation. Without a properly functioning thyroid, bones and muscles will degenerate, as the thyroid has a key role in cellular metabolism and development. In short, iodine must be present for the thyroid to function properly, and the thyroid must function correctly for cells to develop. If individual cells don't develop, they cannot form strong bones and muscles. So, cretinism, or congenital hypothyroidism, is the result of any interruption in this cycle.

There are few cases of cretinism because this case have been resolved. In the market, we can see those formulated milks for pregnant women that are sold. these milks help by providing necessary nutrients that are good for the fetus, especially iodine. With this, cretinism could be avoided. 

Compare and contrast cretinism, myxedema, Grave’s disease, and goiter.

1. Cretinism = hyposecretion of T3/T4 during fetal life and infancy.

a.         dwarfism & mental retardation

b.         prevention = newborn testing

c.         treatment = oral thyroid therapy.

2. Myxedema = hyposecretion during adulthood.

a.         edema, slow heart rate, low body temp, dry hair & skin, muscular weakness, lethargy, weight gain

b.         Oral thyroid hormones reduce symptoms.

3.Grave's Disease = an autoimmune disorder that causes growth of thyroid and   hypersecretion of thyroid hormones, with no negative feedback.

                        a.      enlarged thyroid (2-3x larger)

b.      peculiar edema of the eyes (bulging)

c.    increased metabolic rate, heat intolerance, increased sweating, weight loss, insomnia, tremor, and nervousness.

d.    treatment = surgical removal, use of radioisotopes to destroy some of the thyroid. and anti-thyroid drugs to block

4. Goiter = low thyroid hormones due to iodine deficiency.

                       a.       No thyroid hormones inhibit pituitary release of TSH

                       b.       Thyroid is overstimulated and enlarges, but still functions below normal levels. 

Distinguish between Addison’s disease and Cushing’s syndrome.

Addison’s disease

 

Addison’s disease is typically diagnosed based on assessment of the clinical signs and symptoms described earlier. Laboratory tests are performed to assess electrolyte levels in the blood as well as serum levels of cortisol and ACTH; computed tomography (CT) scans of the adrenal or pituitary glands are sometimes performed as well (Betterle 2002). Low serum cortisol with increased serum ACTH levels is indicative of Addison’s disease (Al-Aridi 2011). Cortisol levels vary according to the time of the day (diurnal variation), with levels normally peaking no later than 8 AM (Lipworth 1999). Therefore, an 8 AM cortisol test is performed to check for cortisol levels in the blood, which are decreased (<3 µg/dL) in Addison’s disease (PubMed 2011b; Lipworth 1999; Betterle 2002). Further, individuals with Addison’s disease do not show an increase in serum cortisol level when given an injection of cosyntropin (a synthetic form of ACTH); this procedure is referred to as an ACTH stimulation test (Betterle 2002; Neary 2010).
On the other hand, people with Addison’s disease specifically due to hypothalamic or pituitary disorders will show low levels of both ACTH and cortisol (Neary 2010). Upon fasting, these individuals often develop very low glucose levels in the blood (hypoglycemia), as their body is unable to produce glucose from stored fat and proteins (Betterle 2002).Abnormally low blood levels of levels of DHEA-sulfate (DHEA-S) along with decreased cortisol and aldosterone levels are indicative of adrenal insufficiency, warranting further testing of HPA axis function (Al-Aridi 2011).

Cushing’s syndrome

 

The typical physical characteristics of Cushing’s syndrome are diagnostic and are further confirmed by laboratory test results. People with Cushing’s syndrome generally have grossly increased levels of free cortisol in their urine and, although cortisol levels normally show diurnal variation, this variation is not observed in Cushing’s syndrome (Papanicolaou 1998). Measurement of ACTH levels can also help to distinguish between the 2 variants of Cushing’s syndrome (ACTH-dependent and ACTH-independent) (Tritos 2012; Newell-Price 2007). Magnetic resonance imaging (MRI) and CT scans are useful for the diagnosis of pituitary and adrenal tumors (Arnaldi 2003; Tritos 2012).

 

Compare and contrast the two types of the disease Diabetes Mellitus.

 

In general, people with diabetes either have a total lack of insulin (type 1 diabetes) or they have too little insulin or cannot use insulin effectively (type 2 diabetes).

• Type 1 diabetes (formerly called juvenile-onset or insulin-dependent diabetes), accounts for 5 to 10 out of 100 people who have diabetes. In type 1 diabetes, the body's immune system destroys the cells that release insulin, eventually eliminating insulin production from the body. Without insulin, cells cannot absorb sugar (glucose), which they need to produce energy.
• Type 2 diabetes (formerly called adult-onset or non–insulin-dependent diabetes) can develop at any age. It most commonly becomes apparent during adulthood. But type 2 diabetes in children is rising. Type 2 diabetes accounts for the vast majority of people who have diabetes—90 to 95 out of 100 people. In type 2 diabetes, the body isn't able to use insulin the right way. This is called insulin resistance. As type 2 diabetes gets worse, the pancreas may make less and less insulin. This is called insulin deficiency.

 

Describe seasonal affective disorder (SAD) in terms of cause, symptoms, and treatment.

Seasonal affective disorder (SAD) is a type of depression that's related to changes in seasons — SAD begins and ends at about the same times every year. If you're like most people with SAD, your symptoms start in the fall and continue into the winter months, sapping your energy and making you feel moody. Less often, SAD causes depression in the spring or early summer.

Symptoms

Major depression

Seasonal affective disorder is a subtype of major depression that comes and goes based on seasons. So symptoms of major depression may be part of SAD, such as:

• Feeling depressed most of the day, nearly every day
• Feeling hopeless or worthless
• Having low energy
• Losing interest in activities you once enjoyed
• Having problems with sleeping
• Experiencing changes in your appetite or weight
• Feeling sluggish or agitated
• Having difficulty concentrating
• Having frequent thoughts of death or suicide

Fall and winter SAD

Symptoms specific to winter-onset SAD, sometimes called winter depression, may include:

• Irritability
• Tiredness or low energy
• Problems getting along with other people
• Hypersensitivity to rejection
• Heavy, "leaden" feeling in the arms or legs
• Oversleeping
• Appetite changes, especially a craving for foods high in carbohydrates
• Weight gain

Spring and summer SAD

Symptoms specific to summer-onset seasonal affective disorder, sometimes called summer depression, may include:

• Depression
• Trouble sleeping (insomnia)
• Weight loss
• Poor appetite
• Agitation or anxiety

 Causes

The specific cause of seasonal affective disorder remains unknown. Some factors that may come into play include:

• Your biological clock (circadian rhythm). The reduced level of sunlight in fall and winter may cause winter-onset SAD. This decrease in sunlight may disrupt your body's internal clock and lead to feelings of depression.
• Serotonin levels. A drop in serotonin, a brain chemical (neurotransmitter) that affects mood, might play a role in SAD. Reduced sunlight can cause a drop in serotonin that may trigger depression.
• Melatonin levels. The change in season can disrupt the balance of the body's level of melatonin, which plays a role in sleep patterns and mood.

Treatment

Treatment for SAD may include light therapy (phototherapy), psychotherapy and medications.

 

References:

http://www.wisegeek.com/what-is-cretinism.htm 

http://webs.ashlandctc.org/mflath/KEY%20ENDOCRINE%20OBJECTIVES.htm

http://www.lef.org/Protocols/Metabolic-Health/Adrenal-Disorders/Page-04

http://www.webmd.com/diabetes/tc/diabetes-differences-between-type-1-and-2-topic-overview

http://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/basics/definition/con-20021047