Sodium balance impaired

In persons with normal kidney function, sodium balance is maintained at a sodium intake of 120 to 150 mEq/day. The fractional excretion of sodium (FENa) is approximately 1% to 3%. Water balance is also maintained, with a normal range of urinary osmolality of 50 to 1200 mOsm/L. In patients with severe CKD (Stages 4 and 5), sodium balance is achieved, but results in a volume-expanded state. FENa may increase to as much as 10% to 20%, possibly due to increased concentrations of atrial natriuretic peptide. An osmotic diuresis occurs with an increase in FENa leading to obligatory water losses and impairment in the kidney s ability to dilute or concentrate urine (urinary osmolality is often fixed at that of plasma or approximately 300 mOsm/L). Nocturia is present relatively early in the course of CKD (Stage 3) secondary to the defect in urinary concentrating ability. Total renal sodium excretion decreases despite an increase in sodium excretion by remaining nephrons. Volume overload with pulmonary edema can result, but the most common manifestation of increased intravascular volume is systemic hypertension. ... 

The ability of the kidney to adjust to abrupt changes in sodium intake is greatly diminished in patients with severe CKD. Sodium restriction beyond a no-added-salt diet should not be recommended except in the face of hypertension or edema. The kidney maintains the ability to lower urinary sodium content to essentially zero, but this can only be accomplished by very gradual sodium restriction over a period of several days. Hospitalized patients should not routinely be sodium restricted because they have adapted to their outpatient intake. Negative sodium balance and its resultant volume contraction can result in decreased perfusion to the kidney and a subsequent further decline in GFR. Saline-containing IV solutions should be used cautiously in patients with CKD because the kidney s ability to excrete a salt load is impaired and such patients are prone to volume overload. Sodium retention and volume expansion contribute to hypertension in many patients with severe CKD, and diuretic therapy or dialysis may be necessary for control of edema or blood pressure. 

Fluid, Electrolyte, and Acid-Base Disorders The volume status of patients with ARF depends primarily on residual urine output and the type of dialysis received, if any. The patient with oliguric ARF will have impaired excretion of sodium and water. In nonoliguric ARF, considerable sodium may be lost in the urine, necessitating replacement to maintain sodium balance. This also applies to the patient who is losing considerable gastric fluids. Patients on CRRT will lose sodium via hemofiltration or dialysis and should be given sodium as part of their CRRT replacement fluid regimen. 

Til tee successive tubule portions contribute to the ASDN the late portion of the distal convoluted tubule, the connecting tubule, and the collecting duct. The recent observation that collecting duct-specific inactivation of aENaC in the mouse kidney does not impair sodium and potassium balance, suggests that the more proximal nephron segments (late distal convoluted tubule, connecting tubule) are mainly important for-achieving sodium and potassium balance. 

If potassium becomes too deficient, changes in body chemistry, water balance, and possibly blood pressure will take place. The sodium content of the heart and other muscle tissue will increase. The heart rate will diminish, and there will be generalized weakness. Reflexes are poor, brain function is impaired, and muscles become soft and unresponsive. Sterility and kidney problems appear. If extreme dehydration is involved, potassium can become drained and proteins break down. The risk of stroke is increased. As I have pointed out before, extreme potassium deficiency can be fatal. If ever you have reason to believe you are low or deficient in potassium. Table 3.2 should be helpful to you. 

Maintenance of fluid volume, osmolarity, electrolyte balance, and acid-base status are aU regulated in large part by the kidney. Homeostasis of sodium, potassium, chloride, calcium, magnesium, and phosphorus is altered due to changes in urinary excretion that occur in patients with impaired kidney function. A comprehensive discussion... 

Isotonic crystalloids, such as 0.9% sodium chloride (normal saline) or lactated Ringer s solution, are used commonly for fluid resuscitation. A patient in septic shock typically requires up to 10 L of crystalloid solution during the first 24-hour period. These solutions distribute into the extracellular compartment. Approximately 25% of the infused volume of crystalloid remains in the intravascular space, whereas the balance distributes to extravascular spaces. Although this could impair diffusion of oxygen to tissues, clinical impact is unproven. 

Most CRF patients retain the ability to reabsorb sodium ions, but the renal tubules may lose their ability to reabsorb water and so concentrate urine. Polyuria, although present, may not be excessive because the GFR is so low. Because of their impaired ability to regulate water balance, patients in renal failure may become fluid overloaded or fluid depleted very easily. 

Sodium Diverse roles including signal transduction Impaired acid-base balance Table salt 1500... 

Absorption route Can enter the body by inhalation or ingestion. Evaporation negligible at 20 C. but harmful concentrations of airborne particles can build up rapidly. Immediate eftects Corrosive to the eyes and respiratory tract. In substantial concentrations can impair consciousness, in serious cases risk of seizures and unconsciousness. Effects of prolonged/repeated exposure Can cause kidney damage, heart rate disorders and disorders of the central nervous system, due to disturbances of the sodium/potassium balance. ... 

The effects of acid waters on fish physiology are similar to those caused by aluminium. For example, fish exposed to acid waters suffer a reduction in blood salts, which could be attributed to an impairment of salt uptake in the gills, and increased sodium use from the brown trout. The salt balance of freshwater fish is maintained by active, energy consuming exchange of ions across the gill membrane and excretion in the urine. Therefore in fish in waters of pH levels between 4.0 and 4.3, particular physiological effects are known to appear in respiration, metabolism and cell volume, and in some cases death can occur. 

An excessive intake of water or excessive retention of water without equivalent intake or retention of sodium can result in hyponatremia, particularly if the mechanisms that control fluid and electrolyte balance are impaired. Altered function of an organ or the hormones that regulate sodium and water (e.g., kidney, pituitary gland and hypothalamus [aldosterone] or adrenal gland [ADH] as well as ANP from the right atria) can cause excess loss of sodium or retention of water and thus can result in hyponatremia. 

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