9 - Altered Mental Status Flashcards
What does altered mental status (AMS) encompass?
A broad range of disorders leading to a change in cognition or level of consciousness.
Clinical presentations include stupor, delirium, and coma.
What is dementia in relation to AMS?
A chronic form of AMS that develops over a prolonged period and is predominant in the elderly.
While not usually life-threatening, it can cause numerous complications.
Why is it important to identify the underlying etiology of AMS?
The differential diagnosis is vast and patients are often unable to provide an accurate history.
Family members or caregivers should be included when obtaining history.
What are common causes included in the differential diagnosis of acute AMS?
- Trauma
- Infection
- Psychiatric disorders
- Vascular issues
- Structural problems
- Hypoxic disorders
- Metabolic disorders
This chapter emphasizes metabolic derangements.
What symptoms did the 25-year-old man exhibit in the case study?
- Stuporous state
- Incoherent rambling
- Repetitive vomiting
- Weight loss
- Excessive fluid intake
- Dry mucus membranes
- Poor skin turgor
- Mild hypoxia
He also exhibited Kussmaul respirations and tachycardia.
What were the laboratory findings for the patient?
Urinalysis showed a pH of 5.5, 4+ ketone bodies, and a specific gravity of 1.035.
EKG revealed sinus tachycardia with peaked T waves.
What is a key term associated with metabolic acidosis in the context of diabetes?
Diabetic ketoacidosis (DKA).
Characterized by hyperglycemia, hyperkalemia, and metabolic acidosis.
What is the primary cause of the problems observed in diabetic ketoacidosis?
Insulin deficiency.
This leads to an acute stress response despite high blood glucose levels.
How is glucose homeostasis maintained in the fed state?
Insulin promotes glucose uptake and storage while counterregulatory hormones facilitate glucose release.
Key hormones include glucagon, epinephrine, cortisol, and growth hormone.
What happens to glucose after a meal?
- Beta cells secrete insulin
- Insulin promotes glucose uptake in adipose and skeletal muscle
- Excess glucose is stored as glycogen
- Some glucose is converted to fatty acids
GLUT4 transporter is insulin-dependent for glucose uptake.
What roles do insulin and glucagon play in glucose metabolism?
Insulin promotes glycogen synthesis and glycolysis, while glucagon promotes glycogenolysis and gluconeogenesis.
They have opposing activities in maintaining plasma glucose levels.
What happens to pyruvate in the fasting state?
Pyruvate is converted to oxaloacetate instead of acetyl CoA due to high NADH levels and glucagon signaling.
This pathway supports gluconeogenesis.
What is the structure of insulin?
A polypeptide hormone produced by the beta cells of the Islets of Langerhans, consisting of two chains (A and B) linked by disulfide bridges.
C-peptide is released alongside insulin and indicates insulin production.
What stimulates insulin secretion from the pancreas?
- Glucose
- Amino acids
- Gastrointestinal hormones
Incretins also promote insulin secretion in anticipation of glucose increases.
How does glucagon affect insulin secretion?
Glucagon stimulates insulin secretion to promote glucose utilization.
Insulin also inhibits glucagon release.
What enzymes are involved in gluconeogenesis?
- Pyruvate carboxylase
- Fructose 1,6-bisphosphatase
- Glucose 6-phosphatase
These enzymes facilitate the conversion of substrates to glucose.
What is the result of glucagon signaling in the liver?
Promotes gluconeogenesis and inhibits glycolysis by affecting key enzymes.
It prevents the conversion of newly made PEP back to pyruvate.
What is the role of pyruvate kinase in metabolism?
Pyruvate kinase is inhibited by glucagon and epinephrine signaling to prevent the conversion of PEP back to pyruvate.
What is the energy requirement for gluconeogenesis?
Gluconeogenesis requires 6 high-energy phosphate bonds to convert 2 pyruvate molecules to 1 glucose molecule.
What process provides energy for gluconeogenesis during fasting?
The energy for gluconeogenesis in the fasting state is obtained from the beta-oxidation of fatty acids.
What happens to acetyl CoA during fasting?
Acetyl CoA accumulates from beta-oxidation and is diverted toward ketogenesis when it exceeds the capacity for oxidation through the TCA cycle.
What is the pathophysiology of hyperglycemia with ketosis in diabetes?
Diabetes is characterized by insulin deficiency or resistance, leading to increased hepatic glucose output and decreased glucose uptake by tissues.
What are the main causes of hyperglycemia in type I diabetes?
The main causes include a severe deficiency of insulin and increased counterregulatory hormones.
What is the effect of cortisol in diabetes?
Cortisol promotes protein catabolism in muscles to supply substrates for gluconeogenesis.
What clinical signs indicate diabetic ketoacidosis?
Signs include hyperglycemia, ketoacidosis, dehydration, and electrolyte loss.
What is the clinical significance of Kussmaul breathing?
Kussmaul breathing is a compensatory mechanism for metabolic acidosis, where the body attempts to remove CO2.
What is the net result of diabetic ketoacidosis?
The net result is hyperglycemia, ketoacidosis, dehydration, and renal dysfunction.
What is the definition of anion gap?
Anion gap measures the difference between serum positively and negatively charged ions, calculated as AG = [Na+] − ([Cl−] + [HCO3−]).
What does an elevated anion gap indicate?
An elevated anion gap indicates the presence of unmeasured anions, often associated with metabolic acidosis.
What are the causes of lactic acidosis?
- Hypoxia * Heart failure * Liver failure * Hypoglycemia * Chronic alcoholism * Vigorous exercise
What metabolic changes occur with alcohol metabolism?
Alcohol metabolism alters intermediary metabolism of carbohydrates, proteins, and fats.
What are the enzymes involved in ethanol metabolism?
- Alcohol dehydrogenase (ADH) * CYP2E1 * Catalase
What is the effect of chronic alcohol consumption on ethanol metabolism?
Chronic alcohol consumption induces CYP2E1, increasing the capacity for ethanol metabolism.
Fill in the blank: In type II diabetes, tissues become _______ to insulin.
[insulin resistant]
True or False: Ketone bodies are formed from glucose metabolism.
False
What is the consequence of osmotic diuresis in diabetes?
Osmotic diuresis leads to dehydration and electrolyte loss, resulting in hyponatremia.
What is the immediate treatment for a patient with diabetic ketoacidosis?
Immediate treatment includes insulin administration, fluid, and electrolyte replacement.
What is the clinical impression for a patient with acute gastrointestinal symptoms and mental status changes?
The clinical impression suggests possible infection, dehydration, and acute metabolic disorder.
What laboratory findings indicate metabolic acidosis in the patient?
Laboratory findings indicate elevated lactate and ketone bodies.
What is the likely cause of hypoglycemia in the patient with a history of alcohol abuse?
The likely cause is impaired gluconeogenesis due to alcohol metabolism.
What is the normal range for anion gap?
The normal range for anion gap is 8-16 mEq/L.
What enzyme primarily metabolizes ethanol?
Alcohol dehydrogenase (ADH) metabolizes about 85% of ethanol.
This is the main enzyme responsible for ethanol oxidation in the liver.
What is the role of CYP2E1 in ethanol metabolism?
CYP2E1 metabolizes 10%-15% of ethanol and is induced by chronic alcohol consumption.
It can also metabolize other compounds like acetaminophen.
What is the consequence of increased CYP2E1 expression in chronic alcoholics?
It increases the capacity for ethanol metabolism, allowing alcoholics to tolerate higher alcohol levels.
This is why alcoholics can ‘hold’ their liquor better.
What is acetaldehyde converted to in the mitochondria?
Acetaldehyde is converted to acetate by aldehyde dehydrogenase (ALDH).
What effect does high NADH/NAD+ ratio have on pyruvate metabolism?
It inhibits the pyruvate dehydrogenase complex, preventing conversion of pyruvate to acetyl CoA, and promotes lactate formation.
This can lead to lactic acidosis.
Fill in the blank: The accumulation of NADH inhibits _______ in gluconeogenesis.
gluconeogenesis.
What metabolic condition can result from high NADH levels during alcohol metabolism?
Hypoglycemia can result from the inhibition of gluconeogenesis.
What is the net result of high NADH levels in the liver during alcohol metabolism?
The net result is hypoglycemia, dehydration, and anion gap metabolic acidosis.
What does steatosis in the liver result from?
It results from increased lipid production and decreased fatty acid oxidation.
What are the consequences of excess acetyl CoA in the liver?
Excess acetyl CoA promotes fatty acid synthesis or ketogenesis, depending on nutritional status.
High NADH favors the formation of beta-hydroxybutyrate.
True or False: Ethanol metabolism leads to increased ketone body synthesis.
True.
What is fomepizole?
A potent inhibitor of alcohol dehydrogenase used to prevent toxic metabolite formation.
What does an elevated osmolality gap indicate?
It indicates the presence of unmeasured solute in the blood.
What is a common sign of isopropanol poisoning?
Ketonemia and ketonuria without acidosis.
What is the primary toxic metabolite of methanol?
Formic acid.
What condition can result from methanol ingestion due to its toxic metabolites?
Profound metabolic acidosis.
What is the primary effect of formic acid on the body?
It inhibits cytochrome c oxidase activity leading to tissue hypoxia.
What is a key symptom of methanol poisoning?
Acute visual changes.
Fill in the blank: Ethylene glycol is commonly used as _______.
automotive antifreeze.
What type of acidosis does ethylene glycol metabolism cause?
Metabolic acidosis.
What is the consequence of propylene glycol toxicity?
Lactic acidosis and potential hepatic and renal dysfunction.
What laboratory result indicates severe metabolic acidosis?
An extremely low bicarbonate level.
What finding is associated with methanol poisoning regarding the optic nerve?
Damage leading to acute visual changes.
What can long-term alcohol abuse lead to in terms of nutritional status?
Malnutrition.
What is the first therapeutic intervention in treating methanol ingestion?
Instill ethanol under direct supervision.
Ethanol competes with methanol for alcohol dehydrogenase, inhibiting the conversion of methanol to its toxic by-products.
What is the significance of the osmolal gap in acute alcohol toxicity?
An osmolal gap >10 mOsm/kg indicates an unmeasured osmotically active molecule, often due to toxic alcohol ingestion.
The osmolal gap develops as the gut absorbs the toxic alcohol into circulation.
What causes the anion gap in toxic alcohol intoxication?
The metabolites of toxic alcohols, specifically organic acids, cause the anion gap.
This occurs after the liver metabolizes the toxic alcohols.
True or False: Isopropanol leads to an anion gap with metabolic acidosis.
False.
Isopropanol is metabolized to acetone rather than organic acids, resulting in an osmolal gap without metabolic acidosis.
What is the role of fomepizole in treating toxic alcohol ingestion?
Fomepizole inhibits alcohol dehydrogenase, preventing the conversion of toxic alcohols to harmful metabolites.
It is often used when ethanol is not available.
What are the high-yield concepts related to toxic alcohols?
- Toxic alcohols are metabolized along the same pathway as ethanol.
- Metabolic products of toxic alcohols cause tissue damage.
- Ethanol slows the formation of toxic metabolites.
- Ethanol infusion can be therapeutic in the absence of fomepizole.
- Osmolal and anion gaps indicate toxic alcohol ingestion.
What is asterixis?
Rhythmic spastic flapping of the hands as a pathognomonic sign of encephalopathy.
Define hepatic encephalopathy.
Mental status changes associated with cirrhosis and metabolic liver failure due to the accumulation of ammonia.
What is noncirrhotic hyperammonemia?
Encephalopathy resulting from failure in the urea cycle to remove ammonia from the system.
Fill in the blank: Urea is synthesized in the liver from ammonia produced by the breakdown of _______.
amino acids.
What is the function of the urea cycle?
It produces arginine, ornithine, and citrulline and removes toxic ammonium ions and free ammonia.
What happens if there are defects in any of the enzymes of the urea cycle?
Accumulation of toxic levels of ammonia occurs.
What might one attribute as the cause for this sudden change in mental status?
A family history of an ill-defined death of a previous male child suggests a genetic cause. The sudden change combined with hypothermia and flaccidity indicates a metabolic emergency.
What does the severely decreased BUN in the neonate indicate?
It could be caused by a low protein diet, malnutrition, or sudden liver failure.
What tests are requested to investigate sudden liver failure?
Liver function enzymes (LFTs), prothrombin time (INR), and serum ammonia levels.
What do normal albumin levels rule out?
Protein deficiency.
What do slightly elevated transaminases indicate in the context of liver function?
While they are slightly elevated, normal bilirubin and alkaline phosphatase levels, along with normal prothrombin time, make acute hepatic failure unlikely.
What does an elevated serum ammonia level suggest?
It brings a urea cycle disorder to the forefront.
What is the normal ammonia level range in neonates?
40-75 μmol/L.
What can the accumulation of ammonia lead to?
Hepatic encephalopathy due to toxic effects on the CNS.
What laboratory analyses are ordered to identify the urea cycle defect?
Amino acid analysis in plasma for citrulline and glutamine, and organic acid analysis in urine for orotic acid.
What does elevated orotic acid in urine and low citrulline indicate?
Ornithine transcarbamylase (OTC) deficiency.
What is the relationship between OTC deficiency and hepatic encephalopathy?
OTC deficiency leads to failure of ammonia removal, causing sudden changes in neuronal function.
What are common presentations of urea cycle disorders in neonates?
Feeding difficulties, lethargy, hyperventilation, hypothermia, seizures, elevated serum ammonia, and depressed BUN.
What can unmask OTC deficiencies in older children and adults?
Metabolic stress such as infection or protein overload.
What happens to the brain and liver if ammonia accumulation goes uncorrected?
Damage to white matter with myelin deficiency and neuronal loss in the CNS, and acute inflammatory process with microvesicular steatosis in the liver.
What does protein turnover refer to?
The synthesis and breakdown of proteins.
What happens to the nitrogen balance in illness?
It tips to the negative.
What are the two mechanisms used to eliminate excess protein?
- Conversion to energy * Urea cycle for ammonia removal.
How does glutamine act as a nitrogen shuttle?
It transports ammonia from peripheral tissues to the liver.
What role do kidneys play concerning ammonia?
They both remove and produce ammonia.
What do enterocytes in the intestine do with glutamine?
Convert it to glutamate and ammonia.
What is the role of alanine in the urea cycle?
It is carried to the liver where it is deaminated to pyruvate.
What are transaminases?
Enzymes that facilitate the transfer of amino groups from amino acids to alpha-keto acids.
What is the significance of ALT and AST in liver disease?
They are markers used to determine hepatocellular injury.
How does the urea cycle eliminate ammonia?
Each urea molecule contains 2 nitrogens, both provided by glutamate.
What are the two transaminases used to determine hepatocellular injury in liver disease?
ALT and AST
What does damage to hepatocytes result in?
Spilling of ALT and AST into the general circulation
How many nitrogens does each urea molecule contain?
2 nitrogens
What is the source of one nitrogen in urea?
Free ammonium from glutamate or glutamine
Where does the urea cycle occur?
In the liver
How many molecules of energy-rich phosphate are required to synthesize one molecule of urea?
Four molecules
What is the first step of the urea cycle?
Synthesis of carbamoyl phosphate
What enzyme catalyzes the synthesis of carbamoyl phosphate?
Carbamoyl phosphate synthetase I (CPSI)
In which cellular compartment does CPSI reside?
Mitochondria
What is the role of N-acetylglutamate (NAG) in the urea cycle?
Allosteric regulator of CPSI
What does OTC deficiency represent?
The most commonly seen inborn error in urea cycle disorders
What is the effect of arginine on the urea cycle?
Stimulates synthesis of NAG and increases production of carbamoyl phosphate
What are the two ammonia-scavenging drugs used to treat urea cycle disorders?
Sodium benzoate and phenylbutyrate
What condition can lead to excess orotic acid in the urine?
Urea cycle disorders, especially OTC deficiency
What enzyme deficiency leads to hereditary orotic aciduria?
Uridine monophosphate synthetase
How does ammonia relate to the development of encephalopathy?
It becomes a neurotoxin when excess in serum and crosses the blood-brain barrier
Which cell type in the CNS detoxifies ammonia?
Astrocyte
What is the consequence of elevated ammonia levels in the brain?
Neurological impairment
What immediate remedies are used for a urea cycle disorder?
Infusion of dextrose, correction of electrolyte and acid-base abnormalities, dialysis
What is the committed step of the urea cycle?
Combining ammonium ion with bicarbonate to form carbamoyl phosphate
What is the result of failure to remove ammonium ions from the body?
Accumulation in the CNS
What is a key finding in urea cycle disorders?
Elevated serum ammonia levels with low BUN
What does the presence of megaloblastic anemia indicate in relation to orotic aciduria?
Differentiates hereditary orotic aciduria from urea cycle disorders
What happens to the balance between excitatory and inhibitory neurotransmitters with rising ammonia levels?
It is disrupted, leading to neural tissue injury
What is the significance of the dark purple urine in the case of the 33-year-old woman?
Indicates possible porphyria or urea cycle disorder
What happens during the synthesis of carbamoyl phosphate?
Ammonium ion combines with bicarbonate and ATP
What is the clinical presentation of OTC deficiency?
Elevated ammonia and low BUN in the serum
What is the role of glutamate dehydrogenase in the CNS?
Converts alpha-ketoglutarate to glutamate
What is the effect of ammonia on the TCA cycle?
Inhibits energy production due to depletion of alpha-ketoglutarate
Fill in the blank: The urea cycle is initiated in the _______.
Mitochondria
Fill in the blank: The enzyme that cleaves arginine to release urea is called _______.
Arginase
What is heme synthesis?
Heme synthesis predominates in the liver and erythroid cells of the bone marrow. Heme is then assembled into hemoglobin, myoglobin, and cytochromes.
What are hemin and hematin?
Pharmacologically stable forms of heme.
What is porphyria?
A disorder of heme synthesis characterized by a series of eight enzyme-mediated reactions.
What are classic pitfalls in the diagnosis of abdominal pain?
Disparity between pain severity and absence of findings, such as in:
* Type 1 diabetes with autonomic neuropathy
* Acute cholecystitis with necrotizing gallbladder
* Mesenteric vascular ischemia
* Heavy metal poisoning
* Shingles
* Porphyria
What symptoms manifest in acute episodes of porphyrias?
Changes in mental status, peripheral neuropathy, severe abdominal pain, nausea, and vomiting.
What is the triad suggestive of porphyria?
Abdominal pain without an obvious cause, seizure activity, and hyponatremia.
How are the porphyrias categorized?
Into three groups:
* Acute hepatic porphyrias
* Cutaneous porphyrias
* Those with both acute pain and cutaneous symptoms
What is the biochemical basis for porphyrias?
Porphyrias result from enzyme deficiencies in the heme synthetic pathway, causing an accumulation of porphyrins and their precursors.
What is the committed step in heme synthesis?
The reaction catalyzed by δ-aminolevulinate synthase (ALAS), which is pyridoxal phosphate-dependent.
What are the 4Ms that induce heme synthesis?
Medication, menstruation, malnutrition, maladies.
What is the most common porphyria?
Porphyria cutanea tarda (PCT), which can be acquired or inherited.
What is the defective enzyme in porphyria cutanea tarda?
Uroporphyrinogen decarboxylase deficiency.
What treatment is used for porphyria cutanea tarda?
Phlebotomy to reduce iron and porphyrin levels.
What is the second most common porphyria?
Acute intermittent porphyria, which is an autosomal dominant disorder.
What is the defective enzyme in acute intermittent porphyria?
Porphobilinogen deaminase.
What are the symptoms of acute intermittent porphyria?
Recurrent attacks of abdominal pain, gastrointestinal dysfunction, and neurologic disturbances.
What is the initial treatment for acute porphyrias?
Infusion of glucose followed by hematin.
What are the consequences of enzyme deficiencies in the heme synthesis pathway?
Accumulation of porphyrins and their precursors.
Fill in the blank: The heme biosynthetic pathway consists of ______ steps.
8
True or False: The quintessential finding of altered urine color in porphyria is apparent at first.
False
What are the major symptoms of cutaneous porphyrias?
Photosensitivity resulting in painful, blistering skin lesions.
What is a common risk factor that can trigger acute attacks of porphyrias?
Conditions that induce heme synthesis, such as medications, stress, or fasting.
What can cause neurological damage in acute intermittent porphyria?
Accumulation of ALA (delta-aminolevulinic acid).
What is a common misconception about patients with porphyria?
That they have psychosomatic pain or are drug-seeking.
What laboratory finding is most likely for a patient with diabetic ketoacidosis due to lack of insulin?
Intracellular potassium level is decreased
Acidosis leads to hydrogen ions entering the cell in exchange for potassium ions, resulting in a net loss of intracellular potassium.
What is the most likely working diagnosis for a 37-year-old man with altered mental status, normal blood glucose, and elevated serum ammonia after high protein intake?
Ornithine transcarbamylase deficiency
The patient is obtunded with normal serum glucose and has mild cerebral edema, suggesting a urea cycle disorder.
What is the most appropriate next step in the management of a patient with accidental methanol ingestion?
Administration of fomepizole
Fomepizole inhibits alcohol dehydrogenase, preventing the formation of toxic metabolites from methanol.
What pharmacotherapy is most appropriate for a patient with acute intermittent porphyria presenting with reddish urine?
Hemin
Reddish urine indicates porphobilinogen accumulation, which is treated with hemin.
What is the most likely explanation for hypoglycemia in a 45-year-old man with alcohol abuse?
Increased NADH/NAD ratio inhibiting gluconeogenesis
Ethanol metabolism increases NADH, blocking substrates needed for gluconeogenesis.
What is the most likely metabolic change after administering glucose and thiamine to a patient in the emergency department?
Increase in triacylglycerol synthesis
Excess NADH from glucose metabolism promotes fatty acid synthesis.
What enzyme deficiency is likely in a 1-month-old child with megaloblastic anemia and orotic aciduria?
UMP synthase (UMPS)
The child’s symptoms and lab findings suggest orotic aciduria due to UMPS deficiency.
What laboratory finding is expected in a child with calcium oxalate crystals and altered mental status?
Increased anion gap
Ethylene glycol toxicity leads to metabolic acidosis with increased anion gap.
What is the underlying cause of acid-base disorder in an elderly female with hyperglycemia and normal BUN?
Gluconeogenesis
The patient presents with diabetic ketoacidosis due to insulin deficiency.
What enzyme is deficient in a patient with elevated levels of δ-aminolevulinic acid and psychiatric symptoms?
Porphobilinogen deaminase
This enzyme deficiency leads to acute intermittent porphyria, presenting with psychiatric symptoms.
What is the relationship between insulin and glucagon in diabetic ketoacidosis?
The ratio of insulin to glucagon is very low in this situation, leading to metabolic acidosis.
What causes the metabolic acidosis in diabetic ketoacidosis?
Increased degradation of triacylglycerols and fatty acids due to insulin insufficiency.
What leads to the synthesis of ketone bodies in diabetic ketoacidosis?
Accumulation of acetyl CoA from beta-oxidation.
True or False: Glycogenolysis contributes to acid-base disorder in diabetic ketoacidosis.
False
What amino acid is primarily carried from muscle breakdown during diabetic ketoacidosis?
Alanine
What is the effect of gluconeogenesis in insulin insufficiency?
Increases the osmolal gap but does not increase the anion gap.
What enzyme deficiency is associated with acute intermittent porphyria (AIP)?
Porphobilinogen deaminase
What are the 4Ms that initiate attacks of acute intermittent porphyria?
- Maladies
- Menstruation
- Medication
- Malnutrition
What laboratory results are significant for diagnosing acute intermittent porphyria?
Increased levels of δ-aminolevulinic acid and porphobilinogen.
What happens with low aldehyde dehydrogenase levels?
Accumulation of acetaldehyde leading to facial flushing, nausea, hypotension, headache, and fatigue.
What condition may cause abdominal pain after a fatty meal?
Lipoprotein lipase deficiency
What is a key symptom of lipoprotein lipase deficiency?
Abdominal pain due to pancreatitis.
What disorder is caused by ornithine transcarbamylase (OTC) deficiency?
Urea cycle disorder
What are the symptoms associated with late-onset OTC deficiency?
Altered mental status and hyperammonemia with orotic aciduria.
