1. Clinical Biochemistry FAQ for GP Trainees Dr Mourad Labib Consultant Chemical Pathologist DGOH NHS Foundation Trust July 2009

2. Plan Common scenarios How best to investigate common problems Gold Standard investigations Advances in Clinical Biochemistry

3. Case 1 A 58-yr old woman with a 5-year history of diabetes (on metformin, simvastatin, ACEI and bendroflumethiazide). She stopped smoking 3 years ago. Mar 09 Sodium 134 potassium 4.8 Urea 3.9 Creatinine 77 What next?

4. Scenario 1 Look at urea Look at previous results Look at her medications Look for weight loss or coughing Check BP for postural drop Low Mar 09 Sodium 134 potassium 4.8 Urea 3.9 Creatinine 77 Oct 08 Mar 08 137 135 4.6 4.3 4.2 4.1 82 79 Chronic On Citalopram No 133/82 & 136/79 Mild SIADH secondary to Citalopram Further investigations: Serum and urine osmolality & sodium

5. Scenario 2 Look at urea Look at previous results Look at her medications Look for weight loss or coughing Check BP for postural drop Low Mar 09 Sodium 134 potassium 4.8 Urea 3.9 Creatinine 77 Dec 08 141 4.6 4.2 82 Acute ACEI Yes 133/82 & 136/79 ?SIADH secondary to bronchial carcinoma Further investigations: Urgent chest x-ray

6. Scenario 3 Look at urea Look at previous results Look at her medications Look for symptoms Check BP for postural drop High Mar 09 Sodium 134 potassium 5.2 Urea 7.9 Creatinine 77 Trend Dec 08 137 4.8 7.2 82 bendroflumethiazide dizziness 118/76 & 105/65 Salt loss: D&V, diuretics, ??Addison’s Further action: consider stopping diuretic, ?synacthen test

7. Case 2 A 61-yr old man with hypertension on Irbesartan (150 mg O.D.) and simvastatin. Jan 09Mar 09 Sodium 141 143 Potassium 4.8 4.6 Urea 5.9 6.3 Creatinine 85 94 e-GFR 84 75 Does he have CKD? Is the change in e-GFR significant?

8. Case 2 Does he have CKD? Check for haematuria & ACR Is the change in e-GFR significant? Jan 09Mar 09 Sodium 141 143 Potassium 4.8 4.6 Urea 5.9 6.3 Creatinine 85 94 e-GFR 84 75 Jun 09 140 4.4 5.7 83 87 Advised to have blood test after avoiding meat the night before Serum creatinine can vary by 10 umol/L and can be affected by diet

9. Case 3 A 68-yr old man presented with tiredness and dry cough. Medical conditions: IHD, hypertension and osteoarthritis (BB, aspirin, ACEI, atorvastatin) Mar 09 Sodium 143 Potassium 6.4 Urea 6.9 Creatinine 97 e-GFR 71 What next?

10. Case 3 Look at urea, creatinine and sodium Look at previous results Look at FBC Check time of collection and receipt at laboratory Normal 5 hours Mar 09 Sodium 143 Potassium 6.4 Urea 6.9 Creatinine 97 e-GFR 71 Nov 08 141 4.7 6.5 93 74 Most likely cause: delay in separation Further action: repeat in plasma and serum ensuring no delay

11. Case 3 SerumPlasma Sodium 143 142 Potassium 5.4 4.9 Urea 6.7 6.6 Creatinine 93 94 e-GFR 74 74 Advise patient to go to RHH for repeat Ensure that you put on request form ‘Plasma potassium’

12. Case 4 A 49-year old man on simvastatin 40 mg daily for 2 years for primary prevention (10-year CVD risk was 22%). He complained of non-specific muscle aches and pains and his CK was raised 336 IU/L (0-190). Question:Do I stop the statin?

13. Case 4 Look at previous CK results Check for activity/exercise Stop statin and repeat CK after 4 weeks Not done He takes part in a walking group (walks 7 miles on Mondays and Thursdays every week) Four weeks after stopping simvastatin, his CK is 290 IU/L ✔ ✔ Raised CK is associated with his exercise and not a side effect of simvastatin Action: Re-introduce simvastatin When checking his CK, do it at least 2 days from the walk!

14. Case 4 Genuine increase in CK as a side effect of statin therapy is very rare and generally occurs with maximum doses (80 mg daily) Mild/moderate increase in CK is generally due to the level of activity/occupation of the patient Many people at middle-age have non-specific aches and pains If a patient is on a lifelong treatment of any drug, he/she is bound to have unrelated symptoms during treatment!

15. Case 5 A 55-year old woman presented with thirst and polyuria. Urinalysis showed glucose ++ FPG8.8 mmol/L HbA1c8.1% ALT84 IU/L ALP92 IU/L Bili14 umol/L Question:Can I start her on simvastatin?

16. Case 5 Mild/moderate increases in ALT and GGT are not uncommon in newly diagnosed diabetes due to fatty liver Action: Start simvastatin Check LFTs after 6-8 weeks FPG8.8 7.6 HbA1c8.1%7.4% ALT84 55 ALP9288 Bili14 13 After 8 weeks

17. Case 6 A 62-yr old Asian woman presented with aches and pains, nausea and heartburn. She had an episode of upper abdominal pain a week before. ALT 49 (7-56) ALP156 (40-120) Bilirubin 21 (3-22) Albumin 39 (35-47) What next?

18. Case 6 Raised ALP could be of bone or liver origin Possibilities: Osteomalacia (Asian with aches & pains) Cholelithiasis (abdominal pain, nausea) Action: Check GGT and Bone ALP ALP 149 (40-120) GGT 98 (10-58) Bone ALP 52 (<60) Scenario 1 U/S liver Scenario 2 ALP 149 (40-120) GGT 38 (10-58) Bone ALP 98 (<60) Serum Vit D

19. Case 7 A 65 yr old woman presented with back pain for 2 months. She has hypertension and mild CCF. She has a past history of breast cancer. She is on Bendroflumethiazide, rosuvastatin and furosemide. Calcium2.74 (2.1-2.6) Phosphate0.82 (0.80-1.40) ALP 96 (40-120) Albumin 46 (35-47) What next?

20. Scenario 1 Look at previous results Check for weight loss Look at FBC and ESR Check for history of renal stones Chronic No Normal Yes Mar 09 Calcium 2.74 Phosphate 0.82 ALP 96 Albumin 46 PTH Nov 08 Feb 08 2.62 2.67 0.91 0.87 88 92 41 42 Most likely cause: primary hyperparathyroidism Further action: repeat serum calcium with PTH (fasting and no tourniquet) Apr 09 2.71 0.82 87 40 9.5 (1-5)

21. Scenario 2 Look at previous results Check for weight loss Look at FBC and ESR Check for history of renal stones Normal Yes High ESR No Mar 09 Calcium 2.74 Phosphate 0.82 ALP 96 Albumin 46 PTH Nov 08 Feb 08 2.42 2.44 0.91 0.87 88 92 41 42 Most likely cause: malignancy Further action: repeat serum calcium with PTH (fasting and no tourniquet) Apr 09 2.82 0.82 87 37 <1.0 (1-5)