Glossary

Knowledge, You Can Trust

Know your kidney’ is an initiative to spread the knowledge about kidney’s basic function, kidney diseases, their diagnosis, prevention, and treatment including Dialysis (Hemo and Peritoneal) and Transplant.

Creatinine Vs GFR

Creatinine is not the actual marker of the Kidney Disease, But GFR (Glomerular Filteration Rate) is!

GFR is estimated by different formulas…also available online. The most user-friendly as can be done bedside is Cockgraft Gault Formula but the best is the CKD-EPI equation.

Cockgraft Gault Formula (>90 ml/mt/m2 is normal!) –

(140 — age) * body weight
(72 * creatinine)

For female candidates, we should multiply this to 0.85

This is used to calculate the dose adjustment for the medicines (because of the ease of use of the formula!).

When the lab says creatinine has high normal values (highest value of the normal range, it’s already reached renal dysfunction… if remains for > 3 months (estimated GFR of <60ml/mt/m2) then we will label it as CKD- Chronic Kidney Disease.

What Our Kidneys Do?

In our body, we have two kidneys with a collecting system. Each kidney contains approximately 10 lakh functioning units known as nephrons- composed of the glomerulus (filtering unit) and its tubule (where active and passive exchange take place). Ureters traverse urine from the kidneys to the urinary bladder. The bladder stores urine till we find appropriate circumstances to voluntarily contract bladder muscle to pass urine out of the body via the urethra.

Kidneys are removing metabolic waste from our body by filtration and active exchange. By doing this they remove wastes mainly urea, creatinine, and uric acid while maintaining optimum levels of fluid, electrolytes (Sodium and Potassium), and acid-base. They also help in the synthesis of blood formation by generating erythropoietin. Activating Vit D3 helps in bone metabolism hence balancing Calcium, Phosphorus, and Parathyroid hormone levels.

Salt Control

Our kidney BALANCE Sodium and Potassium levels. Please note the word BALANCE…it’s not decrease/ increase the levels! If their levels in blood are more, kidneys excrete more…if levels are low, kidneys retain them to avoid their loss and levels reach to normal again! Total intake, excretion and balance of multiple hormones together are responsible for this balance. In kidney disease salt accumulation enhanced fluid accumulation and responsible for increased blood pressure and later swelling over face and feet with respiratory problems.

Fluid Control

Similarly like the salt, kidneys are responsible for fluid BALANCE in our body…balancing intake with excretion and with the help of multiple hormones. In most of the kidney disease fluid accumulation is responsible for increased blood pressure and later swelling over face and feet with respiratory problems. Here fluid restriction and medicine enhances water loss are needed. In few kidney diseases kidney throw out more water out of body even when it’s needed in our body...these diseases require more water intake!

Acid Base Balance

Food converted to bodily parts via multiple metabolic (anabolic and catabolic) processes...metabolic waste including acids generated during this process has to go out of our body! Most of soluble nitrogenous wastes thrown out of body via urine. Also kidneys retain bases as bicarbonate which helps in neutralizing generated acids. In kidney diseases accumulation of acids cause respiratory distress.

Metabolic Waste Removal

Most of the soluble nitrogenous wastes are Urea, Creatinine and Uric acid, excreted out of the body in the form of urine. Kidney diseases decrease their excretion and cause accumulation of these waste products/ toxins in patients body and responsible for generalized weakness, decreased appetite, nausea and vomiting.

Preserve Protein / Nutrients

Kidney act as a filter but not only removed unwanted waste, it preserve needed products like proteins (albumin and few important binding proteins) by active re-absorption. In kidney diseases protein leak cause hypoalbuminemia (low blood protein) which leads to swelling of face and feet.

RBC Production

Erythropoeitin is a needed substance secreted from kidneys which is required to synthesize red blood cells from bone marrow (with “raw material”- iron and B12) hence in advanced stages of Chronic Kidney Disease (CKD) this is the reason of Anemia.

Bone Formation

Vit-D required for calcium and phosphorus balance. Kidney secret 1-alpha hydroxylase which is required for the final activation of Vit-D hence Calcium and Phosphorus balance get disturbed. Low calcium and high phosphorous stimulate Parathyroid Hormone secretion which enhance bone resorption and patients complain of bone pain and backache in CKD advanced stages.

AKI (Acute Kidney Injury)

Patients gave a very short history (days) of decreased urine output and renal dysfunction, usually associated with swelling over the face and feet with decreased appetite and occasionally nausea and vomiting.

The best part is “it is reversible” usually completely but delay in treatment will lead to incomplete/ partial recovery of kidney function.

The worst part is “it may have a stormy course” and delay in treatment can be life-threatening.

Treatment is completely dependent on the cause. Based on the cause of kidney injury we can divide kidney injury into 3 main types –

Pre-renal (before actual Kidney)

In these cases, blood volume decreased (water/ blood loss from body, as in case of vomiting, diarrhea or blood loss from trauma) or blood supply to kidney decreased (any type of shock leads to very low blood pressure or when kidney blood vessels narrowing/ blockade happen). If we are able to maintain blood pressure or volume (of water/ blood) on time its completely reversible.

If we are able to maintain blood pressure or volume (of water/ blood) on time it’s completely reversible.

“Prevention is better than cure” is best suited for this type of kidney injury. Prevention of blood/ volume loss while ongoing loss is happening or supplementing them at the earliest and maintaining BP is needed to avoid its complication- irreversible loss of kidney function and occasionally life-threatening complications!

Renal (Actual kidney is affected!)

In these cases, usually we need early Nephrologists’ attention and in most of the cases kidney biopsy is required to diagnose the exact cause before start of specific treatment. Time is very important…they may become dialysis dependent BUT after specific treatment almost all come out of dialysis and most of them reach to previous good renal function. Delay increase dialysis dependent duration and leads to incomplete recovery!

Post-Renal (After actual Kidney)

Here urine flow is obstructed (by stone, stricture, tumor, prostate) somewhere in between kidney to outward…usually we require uro-surgeon’s help! It’s usually completely reversible but delay will cause partial recovery and electrolyte imbalance.

Outcome of treatment of Acute Kidney injury is completely dependent on “How bad the disease was?” (severity of the disease). Based on the severity we can divide Acute Kidney injury in 5 stages.

“RIFLE” criteria, include five categories (Risk, Injury, Failure, Loss, ESRD)

Risk – To organ, usually completely reversible.
Injury – worse than Risk…but most of them are completely reversible, and few might require transient dialysis support.
Failure – is worse than Injury…but chances of irreversibility increase, most require transient dialysis support, but most come out of it!
Loss – Remain dialysis-dependent for > 4 weeks but <3 months, almost all have residual kidney dysfunction remained.
End stage – Remain dialysis-dependent for >3 months, they ultimately require Renal Replacement Therapy in the form of Hemodialysis/ Peritoneal dialysis/ Transplant.