Kidney Stones/ Renal Calculi

Renal Calculi/ Stones can be formed in the kidney, pelvis or ureter, when the concentration of the 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 are generally composed of calcium salt, uric acid, cystic or struvite (triple salt of ammonium, magnesium and phosphorus).

Calcium stones are caused due to excess intake of calcium oxalate, hypervitaminosis D, hyperparathyroidism, prolonged bed test, renal tubular acidosis, and idiopathic hypercalciuria.

Struvite stones are caused mostly due to urinary tract infection.

Uric acid stones are caused due to impaired purine metabolism with increased urinary excretion of uric acid.

Cystine stones are caused due to hereditary metabolic defect in renal tubular reabsorption.

Hot climates leading to over concentrated urine, changes in pH of urine also predispose to stone formation. Deficiency of Vitamin B₆ and magnesium Also play a role in the causation of these stones.

These stones do not produce any symptoms until they begin to move down the ureter, causing pain. The pain is usually severe and often starts in the flank region, often moves to the groin. The patient experiences blood in the urine, severe pain, weakness and in some cases fever.

The role of the dietary management is to relieve symptoms and prevent further complications.

In acute stage with less than 5mm in diameter, it may pass in the urine by drinking large quantities of fluid especially water and needs no specific treatment. Stones more than 7mm in diameter may require surgical treatment or lithotripsy by which large stones are broken down and excreted in the urine.

It is advisable to have liberal fluid intake, a balanced diet and restrict foods based on the main constituents of the stones.

The diet restrictions for different types of stones are:

Type of stone	Diet restriction
Calcium stones -          Phosphate -          Oxalate	Calcium – 400 – 600 mg Phosphorus – 1000-1200 mg
Struvite stones	Low phosphorus diet
Uric acid	Low purine diet
Cystine	Low methionine diet

Potassium content of food can be reduced by leaching the foods rich in the nutrient by the following methods:

• Wash, peel and cut vegetables into small pieces. Soak in warm water for 2-3 hours. Discard water. Add large volume of fresh water and cook the vegetables. Discard water.
• Peel vegetables and cut into small pieces. Bring to boil in a large quantity of water. Discard excess water and cook in a large volume of fresh water. Discard excess water.

Sources of potassium in the diet (Potassium/100 g vegetable) are as follows:

0 - 100 mg	101 – 200 mg	201 mg and above
Beetroort Bottlegourd Broad beans Cucumber Field beans Green mango Peas Lettuce Fenugreek leaves	Bitter gourd Brinjal Cauliflower Cabbage Carrot Onion (small) Radish white Ladies finger Pumpkin Green tomato	Amaranth Coriander leaves Drumstick leaves Spinach Colocasia Potato Sweet potato Tapioca Green papaya Yam

Sources of sodium, calcium, oxalate and Uric acid are as follows:

Post by Faiz Lahori