PCL 4-Fluid retention

Fluid Balance
- The difference between the amount of water taken into the body and the amount excreted or lost.
- a state in which the volume of body water and its solutes (electrolytes and nonelectrolytes) are within normal limits and there is normal distribution of fluids within the intracellular and extracellular compartments

Compartments of body fluid
- Fluid found within the cells is called intracellular fluid (ICF) and that found outside cells is called extracellular fluid (ECF).
- The extracellular fluid is further divided into that which is found as blood plasma within blood vessels, and that which is found in the microscopic spaced between cells called interstitial fluid.
- Approximately 2/3 of body fluid is intracellular and 1/3 is extracellular. Of the ECF approximately 80% is interstitial fluid and 20% is blood plasma.
- There are some special fluid and compartments including: lymph; cerebrospinal fluid; synovial; aqueous humour/vitreous body of the eyes; endolymph/perilymph in the ears; pleural, pericardial and peritoneal fluid between serous membranes; and glomerular filtrate in the kidneys.
- The major components of these fluids include water and solutes. The solute is mostly comprised of electrolytes

Movement of body fluids
- Substances leave and enter capillaries via three mechanisms: vesicular transport, diffusion, and bulk flow.
- Vesicular transport and diffusion are associated with the movement of solutes
- Bulk flow is the movement of both solvent and solute into the interstitial space. Pressures acting to move substances out of the capillary include blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure (IFOP). Blood colloid osmotic pressure (BCOP) and interstitial fluid hydrostatic pressure act to push substances into the capillary. At the arterial end of the capillary the sum of the outward moving pressures is dominant and substances move into the interstitial fluid (filtration). At the venous end the inward pressure is dominant and the substances move into the capillary (reabsorption).
- The exchange of interstitial and intracellular fluid is controlled mainly by the presence of the electrolytes sodium and potassium. Potassium is the chief intracellular cation and sodium the chief extracellular cation. Because the osmotic pressure of the interstitial space and the ICF are generally equal water typically does not enter or leave the cell. A change in the concentration of either electrolyte will cause water to move into or out of the cell via osmosis. A drop in potassium will cause fluid to leave the cell whilst a drop in sodium will cause fluid to enter the cell. Aldosterone, ANP and ADH regulate sodium levels within the body, whilst aldosterone can be said to regulate potassium

Water retention during premenstrual phase
- Not sure of the real cause
- may be related to hormone fluctuations...
- water retention is part of the premenstrual syndrome (PMS) package. In some women the monthly rise in estrogen turns on the production of the hormone aldosterone. Aldosterone, in turn, causes the kidneys to retain fluids which tends to collect in the breasts and abdomen. Some women gain several pounds during this time.
- Other experts see a sodium link. When your blood breaks down progesterone--as it does a week before your period--your kidneys are prompted to retain both water and sodium. At the same time, a powerful water-retaining substance called anti-diuretic hormone may also be released, further influencing your body to hold onto fluids.
- May be related to blood sugar...
- when a person doesn't eat for many hours, blood sugar gets very low. This causes the body to release adrenaline, which signals the body to let go of some of its stored sugar from cells in order to balance out the blood sugar. When sugar is taken from the cells, they fill up with water, and this is what causes the bloating, weight gain and water retention symptoms in those with PMS.

Water retention during menopause
- Water retention also occurs among women past menopause who take estrogen replacement hormones.
- Hormone Replacement Therapy (HRT) that is taken in a tablet (oral) form, will be absorbed from the intestines and pass immediately through the liver via the liver's portal circulation of blood. Thus the liver may break down a large portion of the hormone dose before it can get into the general circulation to be carried to the body cells.
- This is why higher doses of hormones are required if they are administered in tablet form. In many people this does not cause any problems, whereas in others the liver may either render the hormones ineffective or become overworked by the task of breaking down the hormones.
- In the latter case, side effects such as weight gain, fluid retention, nausea, headaches, high blood pressure or even blood clots may result. In such cases it is best to stop the hormone therapy or change to another form of hormone therapy which is not absorbed from the intestines into the liver.
- It is easy to administer natural hormones in forms that are absorbed directly into the blood circulation before they get to the liver. This enables smaller doses to be used because the hormones have a chance to perform their function on the body cells before the liver breaks them down.
- Often, a women going through menopause and having to deal with water retention will turn to diuretics. Although this is one solution, the problem is that diuretics zap essential potassium from the body. With this, additionally problems associated with osteoporosis can develop.

Where water retention occurs
- Fluid rich with oxygen, vitamins and other nutrients passes all the time from the capillaries (the smallest blood vessels) into the surrounding tissues, where it is known as tissue fluid or interstitial fluid.
- This fluid nourishes the cells and eventually should return to the capillaries. Water retention is said to occur as a result of changes in the pressure inside the capillaries, or changes that make the capillary walls too leaky.
- If the pressure is wrong, or the capillaries are too leaky, then too much fluid will be released into the tissue spaces between the cells. Sometimes so much fluid is released that it cannot all return to the capillaries and remains in the tissues, where it causes the swelling and waterlogging which is experienced as water retention.
- Another set of vessels known as the lymphatic system acts like an "overflow" and can return a lot of excess fluid back to the bloodstream. But even the lymphatic system can be overwhelmed, and if there is simply too much fluid, or if the lymphatic system is congested, then the fluid will remain in the tissues, causing swellings in legs, ankles, feet, abdomen or any other part of the body[

How to Avoid Water Retention
- Pass up drugstore diuretics. Some over-the counter medications intended to relieve menstrual cramp pain also claim to help eliminate premenstrual water weight. Some of these products contain caffeine, which may work as a diuretic.The down side to caffeine, however, is that it also promotes breast pain and tenderness as well as irritability.
- Have some herbal tea. Parsley or uva-ursi tea can help flush out excess water without any harmful side effects. You can find these teas in most health foods stores.
- Check out vitamin B6. Taking up to 250 milligrams of vitamin B6 daily helps reduce premenstrual water retention. This nutrient also reduces fluid build up caused by hormone replacement therapy during menopause. Vitamin B6, however, can be toxic in higher doses and should only be taken under the supervision of a doctor.
- Try calcium. Researchers at the New York Metropolitan Hospital found that a daily calcium supplement provided relief from premenstrual water retention in three-fourths of the women who took it.The best bet is to take a 500-milligram chewable tablet twice daily at breakfast and dinner. Ask your doctor whether these supplements might prove helpful in your case.