What is Chronic Kidney Disease?

Chronic Kidney Disease (CKD) is an alteration in the normal function of the kidneys caused by a chronic process and it is usually not reversible. Functionally, the kidney tissue is less capable of performing its functions which include: the filtration of blood, the control of the acid base status, electrolyte concentration control, fluid and blood pressure management, generation of erythropoietin for red blood cell production and  activation of vitamin D.

The processes that most commonly result in CKD are persistent uncontrolled hyperglycemia from diabetes mellitus, persistently elevated blood pressures, acute or subacute inflammatory conditions of the kidneys and genetically mediated anatomic abnormalities such as polycystic kidney disease (PKD). These processes result in scarring and fibrosis of the kidney tissue, with loss of renal cells in the cortex and medullary portions of the kidneys. 

Chronic kidney disease is usually classified in stages, going from I to V. The function that has been chosen to  assign the stages is the filtration function, measured as a variable called glomerular filtration rate (GFR). Although the kidney has many different functions, they are related to each other. The relationship is not perfect, but is is safe to say that if there is a reduction on the filtration function function of the kidneys, the other functions will be affected, in variable degrees. It is also possible that certain functions of the kidney may be affected with little change in other functions, for example, there are conditions that involve abnormalities in the handling of potassium or acidity without a change in the filtration function or generation of erythropoietin, however, these conditions are not too common.

The final stage of CKD is called end-stage renal disease (ESRD). At this stage, renal replacement therapy (RRT) becomes necessary. RRT includes dialysis (in its different modalities) and renal transplantation.

Marco A. Ramos MD

Stroke: People at Risk and its Consequences

"Stroke" is a the common term for an "acute cerebral infarction", which means injury with loss of neurons of the brain tissue. There are 2 main causes for stroke: the obstruction of one of the arteries that feeds blood to the brain and bleeding from blood vessels in the brain. Both situations are very serious and can lead to loss of brain cells, loss of physical or intellectual function and death.

The people who are at risk for stroke are diabetics, people with high blood pressure, smokers, obese and patients with high cholesterol. If someone already has had a stroke he or she has a higher risk to have another one. In addition, for an individual who has coronary artery disease or peripheral artery disease, there is an increased risk of stroke. Atrial fibrillation (AF; an irregular heart beat) increases the chances of stroke, that is the reason why many persons with AF have to take an anticoagulant (blood thinner). Finally, there are genetic conditions that can increase the risk of stroke. Examples of this are sickle cell disease and increased coagulation disorders such as Factor V Leyden.

Stroke can be a devastating condition for the individual and it is definitely a major public health problem¹ due to the immense cost it represents. It accounts for approximately 320 billion dollars every year in healthcare direct and indirect expenditures². The patient has to deal with loss of function, which could be physical  (paralysis of arms, legs and/or face), and intellectual deficits like the loss memory and inability to speak. The recovery from stroke is usually slow and involves the use different levels of rehabilitation services.

References

1. Hankey GJ. StrokeHow Large a Public Health Problem, and How Can the Neurologist Help?. Arch Neurol. 1999;56(6):748-754. 

2. Mozaffarian D, Benjamin EJ, Go AS, et al. Heart Disease and Stroke Statistics-2016 Update: A Report From the American Heart Association. Circulation. 2016;133:e38-e360.

Marco A. Ramos MD

Who is Obese? 5 Dangers of Obesity

The healthcare community has defined obesity as a body mass index (BMI) of 30 or more. The BMI is the ratio between the weight of a person (in kilograms) and the square of the height (in meters). There are many calculators online that can calculate the BMI using pounds and feet/inches. This is a very inexact way of classifying overweight people because there could be very muscular people that could be obese according to this definition. In addition, it may cause shorter people to be overrepresented in the obese population.  In spite of this, the BMI provides an easy way of classifying people according to weight that can lead to meaningful research and can serve as an effective screening tool.

There are many dangers that originate from being obese. I will list here the five most relevant ones

1. Diabetes mellitus. Having excessive adipose tissue causes insulin resistance and some obese people may become diabetic because of this.

2. Hypertension. Obesity is associated with hormonal variations that may lead to salt and water retention and constriction of small arteries. These changes can elevate the blood pressure.

3. Sleep apnea.  This condition is related to obesity. It causes the breathing to stop many times during the night causing problems with oxygenation and getting rid of carbon dioxide.

4. Osteoarthrosis. The extra weight that the obese person has to carry has an impact on the hip and knee joints. This may lead to incapacitating pain and joint replacement surgeries.

5. Cancer. Breast, colon, gallbladder and endometrial malignancies are more common in overweight individuals than in people with normal weight

Diabetes and hypertension are  significant risk factors for coronary artery disease and stroke. Sleep apnea is directly related to hypertension. This means that obesity may impair a person’s health in multiple ways.

Marco A. Ramos MD

5 Possible Consequences of Uncontrolled High Blood Pressure

Uncontrolled high blood pressure (hypertension) is associated with several health conditions. Hypertension is treatable, so this means that the following diseases can be prevented or delayed. 

1. Heart attacks. Elevated blood pressure is related to atherosclerosis, which, by narrowing the coronary arteries, can lead to heart attacks. Heart attacks can cause congestive heart failure and sudden death. 

2. Impaired vision. Hypertension can cause something called hypertensive retinopathy. This means that the retina (where the images are formed in the eye) can get damaged by chronic high blood pressure and can lead to impaired vision and blindness.

3. Amputation of limbs. High blood pressure can lead to the amputations of limbs, specially feet and legs. The problem starts with the atherosclerosis in the arteries of the limbs which eventually leads to obstruction and lack of blood supply to the feet and legs, especially. Hypertension is related to the atherosclerosis of the limb arteries, just as with the heart.

4. Stroke. The brain can also be the victim of atherosclerosis, which is related with hypertension (as we have just seen). In addition to this, if the blood pressure becomes too high, it can lead to bleeding inside the brain, by rupture of the arteries.

5. Kidney disease. The kidneys are very sensitive. Elevated blood pressure for a long time can cause scarring of the kidney tissue to the point that it cannot perform its functions anymore. The kidneys are important for sodium and potassium control, blood pressure control, generation of red blood cells, vitamin D and calcium metabolism and acid-base balance.

Marco A. Ramos MD

The Three Most Common Causes of Kidney Failure

The kidneys are very important organs in the human body. They perform many functions other than just make urine (see my blog post published on October 23, 2014). The kidneys can lose 80-90% of their total function and there could not be any symptom, however, if more than that is lost, dialysis or kidney transplantation are needed in order to survive. So, what causes kidney failure? The list is long, however, the three most important causes are as follows:

The number one reason for people requiring dialysis is diabetes mellitus. 38-45% of all cases of kidney failure are caused by this condition.

The second cause for kidney failure is hypertension (elevated blood pressure). 25-28% of the people who require renal replacement therapy have hypertension as its main mechanism. We have to keep in mind that many diabetics are hypertensives too.

The third cause for kidney failure is glomerular diseases in general. Many of these conditions are autoimmune and have long and complicated names and can only be diagnosed accurately by a kidney biopsy. 10-15% of dialysis cases are from these conditions.

These three causes account for about 85% of all reasons for going into dialysis. There are other situations like genetic conditions,
medication reactions or toxicity from herbal “remedies” that can also cause the kidneys to fail. Since kidney dysfunction rarely produces symptoms until it is too late, it is important to undergo yearly physical examinations that include basic laboratory workup that would detect that the kidney is failing. 

Marco A. Ramos MD

The Many Functions of the Kidney

The kidney has many vital functions. They can be altered by disease, trauma, medications or intoxications. Although the kidney is widely recognized as the organ which “makes urine” and in the process “cleaning the body from unnecessary substances”, it has many other functions.

The kidney regulates the level of fluid the body has. This function is closely tied with the regulation of the sodium and water contents of the body and with the blood pressure control. If this property fails, the could be high blood pressure, low blood pressure, high sodium or low sodium levels in the blood.

The body is alive because it can keep a tightly regulated pH (or acid-base status). If the blood pH drops below 6.8 or goes higher than 7.6 life is not sustainable. The kidney (together with the lung) is key in the control of the blood acid-base status.

The body needs a sensor to be able to create more red blood cells when they are needed. This sensor is the kidney. There is a hormone called erythropoietin which is secreted when there are less red blood cells or when the blood carries less oxygen.

The bone metabolism needs the kidney to produce activated vitamin D. This hormone is essential for the absorption of calcium from the intestine and to suppress another hormone called PTH, which if not suppressed it can lead to loss of bone mass and loss of phosphorus though the urine.

The body needs to keep a tight control of the potassium concentration in the extracellular fluid. The kidney is in charge to determine how much potassium should be allowed in the urine and how much should be retained.

The kidney has to be able to filtrate certain substances and to keep others. If the kidney were to let all substances be filtered, we would lose important proteins such as albumin and immunoglobulins (antibodies) though the urine.

By doing this quick summary, it is obvious that the kidney is a complex organ. The available forms of dialysis do a good job trying to mimic the function of the kidney, however, they are far away from perfect. The proof of this is how much better the results of kidney transplantation are compared to the results of dialysis.

Marco A. Ramos MD