Hypertension: Alcázar Arroyo R

Alcázar Arroyo R. · Hospital de Fuenlabrada, Madrid. · Nefrologia. · Pubmed #19018744 No free full text.

Abstract: 1. The kidneys are the key organs to maintain the balance of the different electrolytes in the body and the acid-base balance. Progressive loss of kidney function results in a number of adaptive and compensatory renal and extrarenal changes that allow homeostasis to be maintained with glomerular filtration rates in the range of 10-25 ml/min. With glomerular filtration rates below 10 ml/min, there are almost always abnormalites in the body's internal environment with clinical repercussions. 2. Water Balance Disorders: In advanced chronic kidney disease (CKD), the range of urine osmolality progressively approaches plasma osmolality and becomes isostenuric. This manifests clinically as symptoms of nocturia and polyuria, especially in tubulointerstitial kidney diseases. Water overload will result in hyponatremia and a decrease in water intake will lead to hypernatremia. Routine analyses of serum Na levels should be performed in all patients with advanced CKD (Strength of Recommendation C). Except in edematous states, a daily fluid intake of 1.5-2 liters should be recommended (Strength of Recommendation C). Hyponatremia does not usually occur with glomerular filtration rates above 10 ml/min (Strength of Recommendation B). If it occurs, an excessive intake of free water should be considered or nonosmotic release of vasopressin by stimuli such as pain, anesthetics, hypoxemia or hypovolemia, or the use of diuretics. Hypernatremia is less frequent than hyponatremia in CKD. It can occur because of the provision of hypertonic parenteral solutions, or more frequently as a consequence of osmotic diuresis due to inadequate water intake during intercurrent disease, or in some circumstance that limits access to water (obtundation, immobility). 3. Sodium Balance Disorders: In CKD, fractional excretion of sodium increases so that absolute sodium excretion is not modified until glomerular filtration rates below 15 ml/min (Strength of Recommendation B). Total body content of sodium is the main determinant of extracellular volume and therefore disturbances in sodium balance will lead to clinical situations of volume depletion or overload: Volume depletion due to renal sodium loss occurs in abrupt restrictions of salt intake in advanced CKD. It occurs more frequently in certain tubulointerstitial kidney diseases (salt losing nephropathies). Volume overload due to sodium retention can occur with glomerular filtration rates below 25 ml/min and leads to edema, arterial hypertension and heart failure. The use of diuretics in volume overload in CKD is useful to force natriuresis (Strength of Recommendation B). Thiazides have little effect in advanced CKD. Loop diuretics are effective and should be used in higher than normal doses (Strength of Recommendation B). The combination of thiazides and loop diuretics can be useful in refractory cases (Strength of Recommendation B). Weight and volume should be monitored regularly in the hospitalized patient with CKD (Strength of Recommendation C). 4. Potassium Balance Disorders: In CKD, the ability of the kidneys to excrete potassium decreases proportionally to the loss of glomerular filtration. Stimulation of aldosterone and the increase in intestinal excretion of potassium are the main adaptive mechanisms to maintain potassium homeostasis until glomerular filtration rates of 10 ml/min. The main causes of hyperkalemia in CKD are the following: Use of drugs that alter the ability of the kidneys to excrete potassium: ACEIs, ARBs, NSAIDs, aldosterone antagonists, nonselective beta-blockers, heparin, trimetoprim, calcineurin inhibitors. Determination of serum potassium two weeks after the initiation of treatment with ACEIs/ARBs is recommended (Strength of Recommendation C). Routine use of aldosterone antagonists in advanced CKD is not recommended (Strength of Recommendation C). Abrupt reduction in glomerular filtration rate: Constipation. Prolonged fasting. Metabolic acidosis. A low-potassium diet is recommended with GFR less than 20 ml/min, or GFR less than 50 ml/min if drugs that raise serum potassium are taken (Strength of Recommendation C). In the absence of symptoms or electrocardiographic abnormalities, review of medications, restriction of dietary potassium and use of oral ion exchange resins are usually sufficient therapeutic measures (Strength of Recommendation C). If symptoms and/or electrocardiographic abnormalities are present, the usual parenteral pharmacological measures should be used (10% calcium gluconate, insulin and glucose, salbutamol, resins, diuretics) (Strength of Recommendation A). Parenteral bicarbonate and ion exchange resins in enemas are not recommended as first-line treatment (Strength of Recommendation C). Hemodialysis should be considered in patients with glomerular filtration rates below 10 ml/min (Strength of Recommendation C). 5. Acid-Base Disorders in CKD: Moderate metabolic acidosis (Bic 16-20) mEq/L is common with glomerular filtration rates below 20 ml/min, and favors bone demineralization due to the release of calcium and phosphate from the bone, chronic hyperventilation, and muscular weakness and atrophy. Its treatment consists of administration of sodium bicarbonate, usually orally (0.5-1 mEq/kg/day), with the goal of achieving a serum bicarbonate level of 22-24 mmol/L (Strength of Recommendation C). Limitation of daily protein intake to less than 1 g/kg/day is also useful (Strength of Recommendation C). Use of sevelamer as a phosphate binder aggravates metabolic acidosis since it favors endogenous acid production and therefore acidosis should be monitored and corrected if it occurs (Strength of Recommendation C). Hypocalcemia should always be corrected before metabolic acidosis in CKD (Strength of Recommendation B). Metabolic acidosis is an infrequent disorder and requires exogenous alkali administration (bicarbonate, phosphate binders) or vomiting.

Alcázar Arroyo R, Orte Martínez L, Otero González A. · Hospital de Fuenlabrada. Madrid. · Nefrologia. · Pubmed #19018731 No free full text.

Abstract: Chronic kidney disease (CKD), like other chronic diseases, is a serious public health problem because of both its high incidence and prevalence and its significant morbidity and mortality and socioeconomic cost. Advanced chronic kidney disease (ACKD) includes stages 4 and 5 of the CKD classification. It is defined as chronic kidney disease in which there is a severe reduction in glomerular filtration rate (GFR < 30 ml/min). The treatment goals are to reduce and treat the complications associated with chronic kidney failure and to prepare the patient adequately and sufficiently in advance for kidney replacement therapy. The prevalence of ACKD is 0.2-0.6% of the adult population. This prevalence increases with age and in Spain is 1.6% in persons older than 64 years. - CKD is easily detected in clinical practice with simple tests (GFR estimated by equations based on serum creatinine, albuminuria and urine sediment) (Strength of Recommendation B). - It is recommended to detect the presence of CKD in all persons older than 60 years or with hypertension, diabetes or cardiovascular disease (Strength of Recommendation B). - Early detection and appropriate referral to the nephrology of patients with ACKD improves long-term morbidity and reduces costs for both the patient and the health care system (Strength of Recommendation B). Adequate communication and coordination between the primary care and nephrology is essential for this early detection: - Referral to nephrology should be made based on the stage of CKD, age of the patient, rate of progression of kidney failure, degree of albuminuria and presence or appearance of early warning signs.All patients with CKD stages 4-5 should be referred to nephrology (Strength of Recommendation C). - A protocol should be established in each health area for joint follow-up between primary care and nephrology (Strength of Recommendation C). - The creation of multidisciplinary ACKD units including a nephrologist, nephrology nurse, dietitian and social worker allows an integrated approach to the different aspects of management of patients with ACKD and is cost-effective (Strength of Recommendation B).