Chapter 12: Chronic Kidney Disease and Dialysis
What is the definition of chronic kidney disease (CKD)?
Abnormalities of kidney structure or function, present for 3 months or longer, with implications for health.
What are the two primary etiologies of CKD?
How many stages does the National Kidney Foundation use to classify CKD?
What is the definition of stage 1 CKD?
- chronic kidney damage
- normal or slightly ↑ GFR
- ≥90 mL/min/1.73 m2
What is the definition of stage 2 CKD?
- mildly ↓ GFR
- 60–89 mL/min/1.73 m2
What is the definition of stage 3 CKD?
- moderately ↓ GFR
- 30–59 mL/min/1.73 m2
- 45–59 mL/min/1.73 m2 (stage 3a)
- 30–44 mL/min/1.73 m2 (stage 3b)
What is the definition of stage 4 CKD?
- severely ↓ GFR
- 15–29 mL/min/1.73 m2
What is the definition of stage 5 CKD?
- kidney failure (ESRD)
- 75% or more kidney function lost
- <15 mL/min/1.73 m2 (or dialysis)
What are five epidemiological risk factors for CKD?
- sex (male)
- race (African, Native, or Asian)
- cardiovascular disease
What are the four most common causes of ESRD?
- diabetes mellitus (44%)
- hypertension (28%)
- chronic glomerulonephritis (16%)
- polycystic kidney disease (4.5%)
What is the highest risk factor for CKD?
Age older than 60 years
How much fluid do the kidneys filter per day?
What is the functional unit of the kidney?
What are the three basic components of the nephron?
Despite damage to nephrons, patients in the early stages of CKD remain asymptomatic. Why is this?
Nephrons that are lost cannot be replaced; normal renal function is maintained due to compensatory hypertrophy of the remaining nephrons.
What is the minimum percentage of nephrons required to maintain normal kidney function?
What are three morphological changes that occur in the end-stage kidney?
- reduced size
What explains the polyuria that is commonly encountered in CKD?
Renal tubular malfunction causes the sodium pump to lose its effectiveness, which increases sodium excretion, leading to excessive amounts of dilute urine.
What is the term for the clinical syndrome caused by renal failure, retention of excretory products, and interference with endocrine and metabolic functions?
What is the term for accumulation of nonprotein nitrogen compounds in the blood (i.e. urea) due to loss of glomerular filtration function?
What laboratory value measures the level of azotemia?
blood urea nitrogen (BUN)
What acid-base imbalance occurs due to buildup of waste due to CKD?
What compensatory mechanism occurs due to metabolic acidosis of CKD?
What is one of the most common manifestations of ESRD detectable on a CBC?
What are six mechanisms of anemia in CKD?
- iron deficiency
- decreased erythropoietin
- inhibition of erythropoiesis
- bleeding episodes
- shortened RBC survival
What is the term for the tendency toward abnormal bleeding common in patients with ESRD?
What is one of the most common cardiovascular complications of ESRD?
What is the collective terms for the bone disorders seen in ESRD?
How does CKD cause hypocalcemia?
Decreased renal 1-α-hydroxylation of vitamin D reduces intestinal calcium absorption.
How does CKD lead to bone demineralization?
Decreased renal phosphate excretion causes bone to buffer the acid by releasing calcium and phosphates
What hormone is released in response to low levels of serum ionized calcium in CKD?
parathyroid hormone (PTH)
What are excess levels of PTH caused by CKD called?
What are the three main functions of PTH?
- ↓ tubular reabsorption of phosphorus
- ↑ renal production of the vitamin D
- ↑ intestinal vitamin D absorption
What are the three progressive osseous changes that occur in renal osteodystrophy?
- osteitis fibrosa
Which osseous change of renal osteodystrophy is characterized by increased unmineralized osteoid bone matrix?
Which osseous change of renal osteodystrophy is characterized by bone resorption with lytic lesions and marrow fibrosis?
Which osseous change of renal osteodystrophy is characterized by enhanced bone density?
In what stage of CKD do patients begin to show significant signs and symptoms?
What are five signs and symptoms of early CKD?
- weight loss
What are five signs and symptoms of late CKD?
- leg cramps
- dark urine
Why does ESRD cause hyperpigmentation of the skin?
Because of retention of carotene-like pigments normally excreted by the kidney.
Why might a patient with ESRD sometimes notice a whitish coating on their skin?
Because of residual urea crystals left when perspiration evaporates (“uremic frost”).
What is the most basic test of kidney function?
What is the best measure of overall kidney function?
What is the most significant protein in the urine?
What laboratory test is a measure of muscle breakdown and filtration capacity of the nephron?
What laboratory test compares the creatinine concentrations in blood and urine?
Why is BUN a less specific indicator of kidney function compared to creatinine clearance or serum creatinine?
Because it is also influenced by liver function and conditions that affect blood flow.
What is the recommended treatment approach for stage 1 and stage 2 CKD?
Conservative care aimed at decreasing retention of nitrogenous waste products and controlling hypertension, fluids, and electrolyte imbalances.
What is the recommended treatment approach for stage 3 CKD?
Management of anemia, malnutrition, and bone disease (e.g. hyperparathyroidism).
What is the recommended treatment approach for stage 4 CKD?
Care by a nephrologist is recommended, and preparations for renal replacement therapy begin.
What is the recommended treatment approach for stage 5 CKD?
What is dialysis?
A medical procedure that artificially filters blood.
At what value of GFR does dialysis become important?
< 30 mL/minute/1.73 m2
What are the two types of dialysis?
- peritoneal dialysis
What for of dialysis do most patients (88%) receive?
What are the two types of peritoneal dialysis?
- continuous cyclic peritoneal dialysis (CCPD)
- chronic ambulatory peritoneal dialysis (CAPD)
How does peritoneal dialysis work?
A hypertonic solution is instilled into the peritoneal cavity through a permanent catheter, then drawn out after a time along with the dissolved solutes (e.g. urea).
Which type of peritoneal dialysis uses a machine to perform three to five dialysate exchanges while the patient sleeps?
continuous cyclic peritoneal dialysis (CCPD)
Which type of peritoneal dialysis requires manual changes of 1.5 to 3 L of dialysate into the peritoneal cavity, for 30 to 45 minutes, four to five times per day?
chronic ambulatory peritoneal dialysis (CAPD)
What are four advantages of peritoneal dialysis?
- low initial cost
- ease of performance
- reduced risk of infectious disease
- no need for anticoagulation
What are four disadvantages of peritoneal dialysis?
- frequent sessions
- risk of peritonitis
- risk for abdominal hernia
- lower effectiveness
When is peritoneal dialysis indicated?
Its principal use is in patients in acute renal failure or those who require only occasional dialysis.
When is hemodialysis indicated?
It is the method of choice when azotemia occurs and dialysis is needed on a long-term basis.
How long do hemodialysis treatments take and how often are they performed?
About 3 to 4 hours every 2 or 3 days
What is the main method by which hemodialysis is administered?
Through a permanent arteriovenous graft or fistula, usually placed in the forearm.
What percentage of normal renal function is hemodialysis approximately equal to?
What are five complications of hemodialysis?
- viral infections (HBV, HCV, HIV)
- bacterial infections (S. aureus)
- abnormal bleeding
What are three reasons why patients undergoing dialysis may experience abnormal bleeding?
- decreased platelet factor 3
- platelet destruction by mechanical trauma
- activation of prostaglandin I2 (prostacyclin)
When should medial referral be made for a dental patient to screen for CKD?
- if diabetes and hypertension are present
- if other risk factors are present (e.g. smoking)
- if signs and symptoms of CKD are present
At what stage of CKD is consultation with the patient's physician is suggested before dental care is provided?
stage 4 or higher
At what stage of CKD is consultation with the patient's physician about the need for antibiotics recommended?
stage 3 or higher
What tests should be performed for patients with CKD before any invasive procedure is planned for dental?
Pretreatment screening for bleeding disorders, and a platelet count should be obtained.
At what GFR should elective dental care be delayed until medically consultation is obtained by the patient?
At what GFR are drugs that are excreted by the kidneys eliminated approximately twofold less efficiently?
What are five nephrotoxic drugs that must be voided in patients with renal impairment?
- nonsteroidal antiinflammatory drugs (NSAIDs)
What explains the nephrotoxic effect of NSAIDs?
They inhibit prostaglandin synthesis, resulting in vasoconstriction and reduced renal perfusion.
Why is acetaminophen probably safer than aspirin in the short-term for patients with renal impairment?
Although acetaminophen may cause renal tubular necrosis at high doses, it is is metabolized in the liver.
What analgesic can be used as an alternative to NSAIDs and acetaminophen in patients with renal impairment?
What is the only tetracycline that does not worsen renal impairment by inhibiting protein synthesis?
What are six reasons why drug frequency and dosage adjustments are required during advanced CKD besides nephrotoxicity and renal metabolism?
- low serum albumin reduces the number of binding sites for circulating drugs
- uremia modifies hepatic metabolism of drugs (increasing or decreasing clearance)
- antacids can affect acid–base or electrolyte balance, complicating uremia
- larger initial doses may be required in the presence of edema
- smaller initial doses may be required in the presence of dehydration
- aspirin and other NSAIDs potentiate uremic platelet defects
Why should drugs that depress the central nervous system be avoided in the presence of uremia?
Because the blood–brain barrier may not be intact, so excessive sedation may result.
Why must meperidine be avoided in patients with CKD?
Because its metabolite can accumulate, leading to seizures.
At what hemoglobin concentration is general anesthesia contraindicated for patients with ESRD?
<10 g/100 mL
What are ten oral manifestations of chronic renal failure?
- pallor (anemia)
- pigmentation (carotene-like)
- bleeding (petechiae, ecchymosis)
- dry mouth (xerostomia)
- altered taste or small (dysgeusia, dysosmia)
- halitosis ("urine-like" odor)
- infections (candidiasis, parotitis)
- enamel defects (hypoplasia)
- osteodystrophy (radiolucent jaw lesions)
- uremic stomatitis
What rare condition associated with acute renal failure and BUN levels <55 mg/dL is characterized by red, burning mucosa covered with gray exudates and later by frank ulceration?
What condition associated with chronic renal failure is characterized by white patches that can resemble hairy leukoplakia?
Although chronic renal failure is associated with xerostomia, caries not a typical complication. Why not?
Salivary urea inhibits metabolic products of bacterial plaque and increases the buffering capacity of saliva, preventing decreases in pH to cariogenic levels.
What is the classic triad of osseous changes that occur in chronic renal failure?
- loss of lamina dura
- demineralization (“ground-glass”)
What dental side effect may occur in patients with CKD taking calcium channel blockers or cyclosporine?
Can patients with well-managed CKD receive dental care?
When acceptable oral hygiene has been established, there are no contraindications to routine dental care, provided that proper attention is paid to the systemic health of the patient.
What is a risk that must be considered in dental management of patients receiving hemodialysis?
The arteriovenous fistula is susceptible to infection (endarteritis) and may become a source of bacteremia, resulting in infective endocarditis.
Do patients with CKD with intravascular access devices require prophylactic antibiotics?
Antibiotic prophylaxis is not routinely recommended, unless the patient is undergoing incision and drainage.
How does hemodialysis affect risk of infection?
Long-term hemodialysis can increase risk of infection, especially those patients with diabetes.
How does hemodialysis affect bleeding?
Hemodialysis can increase bleeding tendency through physical destruction of platelets and use of heparin.
How should dental treatment be planned around hemodialysis?
The optimal time is usually the day after hemodialysis, because on the day of dialysis, patients are typically fatigued and may have a tendency to bleed.
Hemodialysis may removes some drugs from the blood, shortening their duration of effect. What four factors increase the chance that a drug will be dialyzed?
- molecular weight and size
- degree of protein binding
- volume of drug distribution
- endogenous drug clearance
How does the presence of secondary hyperparathyroidism affect the prognosis of CKD?
High levels of PTH are associated with increased mortality.