1. Diabetes Clinical cases CID please… Chemical Pathology: Y5
Karim Meeran

2. H + HCO3 = CO2 + H2O pH [H+] pCO2 - + Metabolic acidosis
6.92
7.0
7.1
7.22
7.40
7.52
7.70
7.80
Metabolic acidosis
respiratory acidosis
Draw this on your IPAD
Metabolic alkalosis
respiratory alkalosis
pCO2

3. Case 1: 16 year old unconscious. Acutely unwell a few days. Vomiting
Breathless.

4. Case 1: data
pH 6.85
PCO2 = 2.3 kPa (N 4-5)
PO2 = 15 kPa

5. What is the acid/base abnormality?
pH 6.85
PCO2 = 2.3 kPa (N 4-5)
PO2 = 15 kPa
Respiratory acidosis
Metabolic acidosis
Respiratory alkalosis
Metabolic alkalosis

6. What is the acid/base abnormality?
Low pH = acidosis
ie: excess H+ ions
HCO H+ = CO H20
Low CO2 = low bicarbonate

7. What is the acid/base abnormality?
Draw the following graph, which will always tell you the answer:

8. H + HCO3 = CO2 + H2O pH [H+] pCO2 - + Metabolic acidosis
Type in your CID now
H + HCO3 = CO2 + H2O - +
pH [H+]
6.92
7.0
7.1
7.22
7.40
7.52
7.70
7.80
Metabolic acidosis
respiratory acidosis
Metabolic alkalosis
respiratory alkalosis
pCO2

9. What is the acid/base abnormality?
Low pH = acidosis
Low CO2 = low bicarbonate
Metabolic acidosis

10. Case 1: more data. Na: 145, K: 5.0, U 10, pH 6.85, Glucose 25.
Why is he unconscious ?
What is the osmolality ?

11. Case 1: more data. Na: 145, K: 5.0, U 10, pH 6.85, Glucose 25.
Why is he unconscious ? Because brain enzymes cannot function at a very acid pH
What is the osmolality ?

12. Case 1: osmolality : derivation*
Na: 145, K: 5.0, U 10, pH 6.85, Glucose 25.
Osmolality = charged molecules + uncharged =cations anions urea + glucose
(Na, K) (Cl, HCO3)
Since cations = anions, this can be reduced to:
Osmolality = 2(Na+K) U G
Also PO4, SO4, etc

13. Case 1: osmolality : derivation*
Na: 145, K: 5.0, U 10, pH 6.85, Glucose 25.
Osmolality = charged molecules + uncharged =cations anions urea + glucose
(Na, K) (Cl, HCO3)
Since cations = anions, this can be reduced to:
Osmolality = 2(Na+K) U G
What is the osmolality?
Also PO4, SO4, etc

14. Case 1: osmolality
Na: 145, K: 5.0, U 10, Glucose 25.

15. Case 1: anion gap* Cations (Na/K) = Anions (Cl, Bicarb, others)
“Others” known as “anion gap”.
Anion gap = Na + K – Cl – bicarb

16. Case 1: anion gap* Cations (Na/K) = Anions (Cl, Bicarb, others)
“Others” known as “anion gap”.
Anion gap = Na + K – Cl – bicarb

17. Case 1: anion gap* Cations (Na/K) = Anions (Cl, Bicarb, others)
“Others” known as “anion gap”.
Anion gap = Na + K – Cl – bicarb
Normal AG = – 102 – 24 = 18 mM

18. Case 1: anion gap* Anion gap = Na + K – Cl – bicarb
Normal AG = – 102 – 24 = 18 mM
In this patient:

19. Case 1: anion gap* Anion gap = Na + K – Cl – bicarb
Normal AG = – 102 – 24 = 18 mM
In this patient calculate the anion gap now:
– 96 – 4.0

20. Case 1: anion gap* Anion gap = Na + K – Cl – bicarb
Normal AG = – 102 – 24 = 18 mM
In this patient: –
= (high)
Suggests extra anions (Ketones)

21. Case 2:
A 19 year old known to have type 1 diabetes for several years presents unconscious.
Results: pH 7.65
PCO2 = 2.8 kPa
Bicarb = 24 mM (normal)
PO2 = 15 kPa
What is the acid-base abnormality ?

22. Case 2: What is the acid/base abnormality?
pH 7.65
PCO2 = 2.8 kPa
Bicarb = 24 mM (normal)
PO2 = 15 kPa
Respiratory acidosis
Metabolic acidosis
Respiratory alkalosis
Metabolic alkalosis

23. What is the acid/base abnormality?
High pH = alkalosis
Low CO2 = respiratory

24. H + HCO3 = CO2 + H2O pH [H+] pCO2 - + Metabolic acidosis
6.92
7.0
7.1
7.22
7.40
7.52
7.70
7.80
Metabolic acidosis
respiratory acidosis
Slows down spontaneously
Primary hyperventilation
Metabolic alkalosis
respiratory alkalosis
pCO2

25. What is the acid/base abnormality?
High pH = alkalosis
Respiratory alkalosis

26. Further results: Na = 140, K=4.0, bicarb=24, Cl=100 Glucose 1.3 mM
What is the anion gap?
What is the diagnosis ?

27. Further results: Na = 140, K=4.0, bicarb=24, Cl=100 Glucose 1.3 mM
What is the anion gap? (normal)
What is the diagnosis ?

28. Further results: Na = 140, K=4.0, bicarb=24, Cl=100 Glucose 1.3 mM
What is the anion gap? (normal)
What is the diagnosis ? Anxiety caused by hypoglycaemia.

29. Case 3.
60 year old man presents unconscious to casualty, with a history of polyuria and polydipsia. Investigations reveal:
Na: 160, K: 6.0, U 50, pH 7.30, Glucose 60.
What is the osmolality ?
Why is he unconscious ?

30. Case 3.
60 year old man presents unconscious to casualty, with a history of polyuria and polydipsia. Investigations reveal:
Na: 160, K: 6.0, U 50, pH 7.30, Glucose 60.
What is the osmolality : mosm/kg
Why is he unconscious ?

31. Case 3.
60 year old man presents unconscious to casualty, with a history of polyuria and polydipsia. Investigations reveal:
Na: 160, K: 6.0, U 50, pH 7.30, Glucose 60.
What is the osmolality : mosm/kg
Why is he unconscious : because the brain is VERY dehydrated.

32. Case 4.
59 year old man known to have type 2 diabetes, on a good diet and metformin presents to casualty unconscious:
Urine is negative for ketones.
Na: 140, K: 4.0, U 4.0, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
What is the osmolality :
What is the anion gap:
What is the acid-base disturbance
Why is he unconscious :

33. Case 4.
59 year old man known to have type 2 diabetes, on a good diet and metformin presents to casualty unconscious:
Urine is negative for ketones.
Na: 140, K: 4.0, U 4.0, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
What is the osmolality :
What is the anion gap:
What is the acid-base disturbance
Why is he unconscious :

34. Case 4. What is the osmolality :
Na: 140, K: 4.0, U 4.0, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
Osmo=2(Na+K) + U + G

35. Case 4. What is the anion gap:
Na: 140, K: 4.0, U 4, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
Urine is negative for ketones.
Anion Gap = (Na+K) - bic - chloride

36. Case 4. What is the anion gap:
Na: 140, K: 4.0, U 4, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
Urine is negative for ketones.
Anion Gap = (Na+K) - bic - chloride

37. Case 4. What is the anion gap:
Na: 140, K: 4.0, U 4, pH 7.10, Glucose 4.0
PCO2=1.3 kPa. Cl = 90. Bicarb = 4.0 mM
Urine is negative for ketones.
Anion Gap = (Na+K) - bic - chloride
ie: there are an excess of anions

38. What is the acid/base abnormality?
pH 7.10
PCO2 = 1.3 kPa (N 4-5)
PO2 = 15 kPa
Respiratory acidosis
Metabolic acidosis
Respiratory alkalosis
Metabolic alkalosis

39. Case 4. What is the acid-base disturbance? pH 7.10 (acidosis)
pCO2 = 1.3 kPa (very low)

40. Case 4. What is the acid-base disturbance? pH 7.10 (acidosis)
pCO2 = 1.3 kPa (very low)
Metabolic acidosis

41. Case 4. ie: there are an excess of anions Not ketones What else ?
Methanol, ethanol, lactate
Metformin in overdose can cause a lactic acidosis
Lactate = 10 mM (N<2.0)

42. The Cori cycle: Glucose (muscle) Lactate Glucose Lactate circulation
Inhibited by metformin
liver

43. Case 4. Why is he unconscious? pH 7.10 (acidosis)
The brain cannot function in such an acidic pH.

44. Definition (type 2 diabetes)
Fasting glucose > 7.0 mM
Glucose tolerance test (75 grams glucose given at time 0)
Plasma glucose > 11.1 mM at 2 hours
(2h value 7.8 – 11.1 = impaired glucose tolerance).

45. Acid base graph: CID