Healthy kidneys help regulate the amount of water, minerals and electrolytes in the body. A proper diet is essential for everyone, but especially important for patients suffering from chronic kidney disease (CKD) and end-stage renal disease (ESRD). The kidneys work around the clock 24/7, 365 days a year. Those with diminished function need to adjust the diet to maintain the delicate balance. If the individual is on dialysis, the diet needs to change accordingly, because the dialysis machine can’t completely replace the constant work which the kidneys perform. A proper diet can help manage the chronic kidney disease (CKD) and potentially prevent the disease from progressing or developing. Of course not every case is preventable, but eating better in general will help to live a higher quality life. GENERAL PRINCIPLES OF DIETARY MANAGEMENT IN RENAL DISEASES Several common principles apply to the dietary management of various renal diseases. This is because symptoms, clinical and biochemical manifestations may be common in different renal disorders. The general dietary principles:  Energy: It should be normal or increased in case of weight loss. A simple diet low in proteins, moderate to high in carbohydrates and unsaturated fats is preferred.  Protein: The amount of protein to be given is dependent on GFR (Glomerular filtration rate). Proteins must be enough to prevent muscle wasting and malnutrition, but it needs adjustment to prevent accumulation of nitrogenous wastes in the blood and uremia. Good quality proteins from milk and eggs are recommended to meet the body’s need for essential amino acid and yet not burden the body with excess non-essential amino acids.  Electrolytes: Sodium intake mostly needs restriction depending on whether it is retained in the body or excessive loss in urine occurs. Retained sodium and water can result in edema, hypertension and congestive cardiac failure (CCF). Potassium (K), if retained, needs restriction to prevent hyperkalemia (excess K in blood), which can result in cardiac arrest. Both electrolytes, if lost in excess amounts in urine may need replacement.  Vitamins and Minerals: 1. Calcium may require supplements in chronic or severe cases along with vitamin D. 2. Phosphate mostly needs restriction as it tends to be retained in the body. 3. Iron supplements are needed with impaired erythropoietin synthesis. 4. Vitamin B and C supplements ate required due to increased needs in renal patients.  Fluid: This mostly has to be restricted due to a fall in the GFR in most patients. If however, polyuria occurs, fluid needs may increase. ACUTE AND CHRONIC NEPHRITIS Nephritis refers to the inflammatory disease of the nephrons due to infection, degenerative processes or vascular disease. In most cases, the inflammatory process affects the capillaries of the glomeruli, this disorder is termed as glomerulonephritis (GN). There may be damage to the tubules also. The most common and well understood of the different types of glomerulonephritis, is post streptococcal proliferative glomerulonephritis. GN may be self-limiting or progress to serious renal damage. Etiology: • Acute form of glomerulonephritis is commonly seen in 3-10 year old children, although in 5% or more cases the initial attack occurs in adults past the age of 50 years. Previous streptococcal infection, 7-20 days prior to onset, is a common cause of this disease and antigen-antibody reaction is mostly the basis of damage of nephrons. In acute glomerulonephritis, there is a usually sudden onset and the condition is usually completely cleared in a year or two. In chronic cases, progressive renal damage occurs involving an increased amount of renal tissue, eventually requiring dialysis and other support treatments Clinical Symptoms of Glomerulonephritis:  .Fever ie. elevation of body temperature above 98.4'F or 37C.  Uremia: accumulation of nitrogenous waste products and other urinary constituents in blood, particularly hematuria (presence of blood in urine) and proteinuria (protein in the urine).  Edema: fluid and electrolyte retention in tissues.  Hypertension: Systolic and Diastolic blood pressure above 120/80 mm Hg  Oliguria (reduced urine output) and anuria (no urine output) because of reduced GFR. Dietary Management:  Calories: A high-energy diet is recommended to spare the proteins for tissue repair rather than being used for energy. Adults may need 30-40 Kcal/kg dry weight and children about 100 Kcal/kg dry weight or more, based on age. Increased energy requirements are also recommended since elevation of body temperature i.e. fevers may be present in patients with glomerulonephritis. Elevation of body temperature results in increase in basal metabolic rate (BMR) and hence the energy intake may be increased to about 10%.  Proteins: Blood urea nitrogen (BUN) and oliguria determine the restriction of protein in the diet. Initially, 0.5 to 0.6-g protein/kg is provided using principally high quality protein. Normal levels of protein (1g/kg IBW) may be provided if BUN levels remain within the normal range. Emphasis should be to include good quality protein or proteins of high biological value (milk and milk products, egg white, meat etc.) in the diet of the patients.  Carbohydrates: Liberal carbohydrate intake is important for protein sparing action for reducing catabolism of protein, as well as, for preventing starvation ketosis. Both simple carbohydrates such as sugar, as well as, complex form such as starches can be included in the diet.  Fats: Based on tolerance levels, fat is included to provide non-protein calories for energy needs. Being energy dense, fat reduces the bulk of the diet and makes the diet more palatable.  Sodium: The restriction of sodium is dependent on the degree of oliguria and hence sodium retention. If renal function is impaired, sodium may be restricted to 500 to 1000 mg/day. With recovery, the intake may be increased. Few sodium-rich foods are: baking soda, salt, ajinomoto, salted wafers, popcorns, salted biscuits, salted namkeens, Papads - all varieties, salted pickles, chutneys, curry powder -commercial, pulses and legumes-all varieties, vegetables such as-cauliflower, snake gourd, bee root, carrot, coriander leaves, fenugreek(methi) leaves, lettuce, spinach (Palak), amaranth, radish, etc which has to be avoided in the diet.  Potassium: In case of oliguria, renal clearance of potassium is impaired resulting in hyperkalemia (increased level of potassium in blood). In the initial stages, therefore potassium may have to be restricted to 1200-1500 mg/day. In addition, fruits, fruit juices, nuts and coconut water may be restricted or avoided, as they are rich in potassium  Fluid: Intake or fluids needs to be restricted in ease of reduced GRF (Glomerular filtration) and oliguria to 500-700 ml/day plus the volume of urine output in previous 24 hours. Without oliguria fluid intake may be normal. END STAGE RENAL DISEASE (ESRD) The condition when kidneys have lost all or most of their ability to function with GFR (Glomerular filtration rate) <5 ml/minute is called end stage renal disease (ESRD). The treatment of choice includes dialysis: hemodialysis (HD) and peritoneal dialysis (PD) and kidney transplantation. Dialysis The process of dialysis involves cleansing the blood of metabolic wastes, based on the principle of osmosis and diffusion. A semi permeable porous membrane is used in dialysis to separate the patient blood carrying excess fluid and metabolic wastes and the hypotonic "dialysis fluid" called dialysate. Through osmosis and diffusion, the metabolic waste and excess water move into the dialysate. The pores of the semi permeable membrane do not permit large particles like protein and RBC to pass through, but smaller water-soluble molecules can pass. The two types of dialysis are: 1) Hemodialysis: In this, patient's blood circulates outside the body through what is commonly referred to as an "artificial kidney machine". An opening is created to connect an artery and a vein, Blood leaves the body via the artery, into the dialyser and after cleansing, flow back to the body via the vein. 2) Peritoneal dialysis: In this, the patient's peritoneum is used as the semi permeable membrane and excess water and metabolic wastes are removed by injecting the dialysis fluid into the peritoneal cavity. After some time, the fluid with the metabolic waste is drained out from the peritoneum. Peritoneal dialysis is less effective than hemodialysis and can result in loss of intact large molecular proteins. For long-term use, continuous ambulatory peritoneal dialysis (CAPD) may be used based on facilities available. In this, the dialysis fluid is exchanged 4-5 times daily. It is important to prevent/control infection. In some cases, continuous cyclic peritoneal dialysis CCPD or Intermittent Peritoneal Dialysis (IPD) may be used. Dietary Management during Dialysis Once dialysis is started, the diet in ESRD can be liberalized, taking care that accumulation of metabolic wastes and water is prevented between treatments and biochemical balance is maintained. • Energy: Upto 35-40 Kcal/kg/day for adults and 100 Kcal or more /kg/day for children is recommended to meet the body needs and minimize tissue protein breakdown. Fats and carbohydrates are the main energy sources used. Some restriction of total and saturated fats may be needed as dialysis patients are prone to cardiovascular disease. • Protein: The requirement is increased due to losses in the dialysate. In hemodialysis, 1.2-1.5 g/kg/day is required. At least 70% of the protein given should be of high biological value from eggs, fish, chicken and milk, though milk may need to be limited being a rich source of potassium. This protein intake helps to maintain positive nitrogen balance, replace losses and prevent undue accumulation of nitrogen wastes, between treatments. Amino acids replacement may also be required in case of large losses. • Sodium: A daily intake of 1500 to 2500 mg may be permitted to control fluid retention and hypertension. This restriction helps to prevent pulmonary edema or congestive heart failure because of fluid overload. Regular assessment of the kidneys ability to handle sodium and water is important to determine the intake. • Potassium: A daily intake of 1500-2500 mg is prescribed to prevent hyperkalemia. Potassium accumulations easily cause cardiac arrhythmias or cardiac arrest. • Phosphorus: This may need some restriction. • Vitamins and Minerals: A daily supplement of water-soluble vitamins and minerals are usually given, as these are lost in the dialysate. Fat-soluble vitamins may be retained. Thus, their supplements are avoided except vitamin D. Supplements of minerals like calcium, iron and zinc are recommended. • Fluid: Usually 400-500 ml (basal losses) plus the urine output is recommended. The fluid intake must take into account all sources of fluid input and output to maintain balance. Mild fluid retention between treatments usually occurs. Kidney Transplantation Kidney transplantation, is a procedure that surgically places a healthy kidney from a donor into the recipient's body: This new kidney does the work of the failed kidneys. Donated kidneys may come preferably from blood relatives after tissue and blood matching. Success of kidney transplant has improved with the use of immunosuppressive drugs and steroids to prevent organ rejection and infection. Post-transplant nutritional support is required for this major surgical procedure. Optimal energy and protein intake are important for recovery. Initially, while on medication, some restriction of sodium, simple sugars, total fat, cholesterol and saturated fat may be required. This is because of the side effects of immunosuppressant and steroids. With recovery and reduction or withdrawal of medication, the diet can be normalized. RENAL CALCULI Renal calculi or stones may be formed in the kidney, pelvis or ureter, when the concentration of components in the urine reaches a level in which crystallization is possible. The process of stone formation is also called nephrolithiasis or urolithiasis. A kidney stone is a solid mass that consists of a collection of tiny crystals. There can be one or more stones present at the same time in the kidney or in the ureter. They generally are composed of calcium salt, uric acid, cystic or struvite (triple salt of ammonium, magnesium and phosphorus). Crystals of these substances interspersed in an organic matrix or base can form stones of varying size. Etiology: Kidney stones may form when the urine becomes too concentrated with certain substances. These substances may create small crystals that become stones. Different types of stones form under different circumstances. Some possible etiological factors in different types of calculi are enumerated: 1) Calcium stones (oxalate, phosphate and carbonate): Excess intake of calcium oxalate, hypervitaminosis D, hyperparathyroidism, prolonged bed rest, renal tubular acidosis, idiopathic hypercalciuria. 2) Struvite stones: Mostly due to urinary tract infection (UTI). 3) Uric acid stones: Impaired purine metabolism with increased urinary excretion of uric acid. 4) Cystine stones: Hereditary metabolic defect in renal tubular reabsorption. Hot climates leading to over concentrated urine, changes in pH of urine also predispose to stone formation. Although there is a high intake of animal protein, deficiency of vitamins B, and magnesium are reported to play a role in the causation of these stones. Some types of stones tend to run in families. Some types may be associated with bowel disease, ileal bypass for obesity, or renal tubule defects. Clinical Symptoms: The kidney stones may not produce symptoms until they begin to move down the ureter, causing pain. The pain is usually severe and often starts in the Rank region, then moves down to the groin. The patient experiences blood in the urine, severe pain, weakness and in some cases fever Laboratory examination and chemical analysis can help determinate location, size and main constituent of stones to determine the treatment. Dietary Management: The goal of treatment of renal calculi is to relieve symptoms and prevent further complications. Treatment, therefore, varies depending on the type of stone and the extent of symptoms or complications. Kidney stones usually pass on their own. In acute stage with stones less than 5 mm in diameter, it may pass in the urine by drinking large quantities of fluid especially water and needs no specific treatment. Stones more than 7 mm in diameter may require surgical treatment or lithotripsy by which large stones are broken down and excreted in the urine Although, role of diet in the formation of urinary stones is not well established, it is advisable to have liberal fluid intake, a balanced diet and restrict foods based on the main constituent of the stones. Besides liberal fluid intake and some dietary restriction, urine pH control helps based on the chemical composition of the stone, mainly via acidifying or alkalinizing agents or diet. Binding agents to bind the stone constituent may also be used.