Metabolism of Ketone Body following the syllabus of Medical Biochemistry of MBBS course

2. Definition Significance Synthesis
Utilization Ketosis

3. Acetone
Acetoacetate
β- hydroxybutyrate
» Ketone bodies are
metabolic products
that are produced in
excess during
excessive breakdown
of fatty acids.

5. Alternate sources to
glucose for energy
Production of ketone bodies under
conditions of cellular energy deprivation
Utilization of ketone
bodies by the brain

6. Ketone
bodies are
synthesized
only in liver

7. Substrate Acetyl-coA
Product Ketone bodies
Compartment Mitochondria
Site Liver
Nature Anabolic

8. Ketogenesis

9. Level
1
Lipolysis (FFA)
INSULIN
GLUCAGON
Level
2
Entry of FFA to
mitochondria
(CPT-1 gateway)
Fed
state/Starv
ation
Level
3
Oxidation of
acetyl CoA
OXALOACET
ATE

10. Utilization (Ketolysis)
• Extrahepatic tissue (muscle, brain)
• Not in cell lack mitochondria (RBC)
Excretion
• Kidney (β-hydroxybutyrate)
• Lung (Acetone)

11. » Ketone bodies are not utilized in the liver
» Enzyme CoA transferase (thiophorase) is
absent in liver
» Utilized in extrahepatic tissues such as brain,
heart, skeletal muscle & kidney
» Ketone bodies serve as fuel for EHT

12. Substrate Ketone bodies
Product Acetyl-coA
Compartment Mitochondria
Site Extrahepatic tissue
Nature Catabolic

13. β-Hydroxybutyrate
CoA transferase
Thiolase
Ketolysis

14. Harper’s illustrated Biochemistry 31st edn P-212

15. Harper’s illustrated Biochemistry 31st edn P-213

16. Definition Causes
Biochemical
findings
Diagnosis management

17. Higher than normal quantities of
ketone bodies present in the blood
or urine constitute ketonemia or
ketonuria, respectively. The
overall condition is called ketosis

18. • Carbohydrate deprivation
Prolonged starvation
• Impaired uptake of glucose by the peripheral tissues
Uncontrolled diabetes mellitus
• High fat feeding
• Severe exercise in postabsorptive stage
Non-pathologic form

19. ↓ Insulin
↑ Epinephrine
Glucagon
↑ Lipolysis
↑ Free fatty acids in plasma
↑ Hepatic output of ketone bodies
Ketoacidosis

20. Ketonemia
Ketonuria
Acetone breath
Metabolic acidosis
Hyperkalemia
• In plasma
β hydroxybutyrate
• In urine
• Rothera’s test
Acetoacetate

21. • Starvation – carbohydrate
ingestion
• Diabetes mellitus – glucose
and insulin
Provision of
glucose to the
tissues
• Bicarbonate administration
Reverses hyperkalemia
Correction of acid-
base and
electrolyte
imbalance