Haematology, biochemistry, microbiology, cellular ...

Case 1 (immunology /Haematology/ Cellular Pathology/) A 53- year- old woman with long standing ulcerative colitis, presented to her GP with a 5 -month history of weakness & fatigue. She also reported a weight loss of 16lbs over the time period. Her physical examination was unremarkable; her abdomen was soft and non-tender with no hepatosplenomegaly. Rectal exam did not reveal any masses or haemorrhoids. Her laboratory findings were:WBC 5200 cells/mm3(4500-11000); Hb 7.5 g/dL(13.5-17.5);Hct 26%(35-48);RBC count 3.5 x 106 cells/mm3(4-6);platelet count 650000 cells per mm3(150000-450000); MCV 55mm3(80-100); reticulocyte count 1.5%(0.5-1.5); urea 15 mg/dL(7-21); creatinine 1.1 mg/dL(0.6-1.1) ;total bilirubin 0.9 umol/dL(0.5-2.5); total calcium 9.2 mg/dL(8-10) Ferritin 8 ng/ml(12-150);CEA 6 ng/ml( < 3 ng/ml). Abdominal ultrasound was normal. Colonoscopy revealed a mass approx. 6 cm in the ascending colon. A biopsy was taken and histology revealed a poorly differentiated adenocarcinoma. Abdominal CT showed an apple-core lesion in the same area as seen by colonoscopy. No liver lesions were found. Chest CT was unremarkable. 2 units of packed red cells were given and once the Hct reached 38% a right hemicolectomy was performed. Pathology of specimen confirmed adenocarcinoma invading through the muscularispropria into the pericolic fat. 4/21 pericolic lymph nodes were found to be positive for metastatic carcinoma. The cancer was staged as T3N2M0 or Stage lllC. The post op CEA was 0.2 ng/dL. The patient was subsequently referred to oncology for chemotherapy 1. Discuss the immunological mechanisms that might contribute to the pathology of ulcerative colitis (20 marks) 2. Discuss how the blood cell indices can be used to determine the underlying cause of the anaemia (low haemoglobin concentration), i.e. whether it’s likely to be blood loss, suppression of red cell production or impaired iron handling. (20 marks) 3. Discuss the role of histological investigations in supporting a diagnosis and decisions on treatment for this patient (20 marks) Case 2 (Microbiology/Clinical Biochemistry) A 17- year-old girl, Sue Jones presents to the Emergency Department with a two day history of vomiting. Her mother was concerned because her daughter appeared drowsy and confused. Sue has been feeling unwell for the past three weeks with excessive thirst & increased urinary frequency associated with a weight loss of 4 kg . Miss Jones’ breathing is deep & sighing and her breath smells sweet. Miss Jones has no prior history of diabetes or other medical problems. Her oxygen saturation are 99% on room air. Her pulse is 110 bpm and her bp is 90/40 mmHg. Her temperature is 37.7C.Her capillary refill time is increased at 3 seconds (indicating decreased peripheral perfusion) and her hands feel cool to touch. Her mucous membranes are dry and there is increased skin turgor, both signs indicating dehydration. Urinalysis revealed 4+ glucose and 3+ ketones. Capillary blood glucose reading was 25mmol/L(4.5-5.6).Her venous blood gases showed the following: pH 7.01((7.35-7.45) pCO2 2.8 kPa(4.9-6.1), pO2 6.8 KPa(10-13), HCO 3 10.2mmol/L(24-28) base excess -18.6mEq/L(-3-+3), glucose 25.9 mmol/L(4.5-5.6). The capillary beta-hydroxybutyrate level was 4.5 mmol/L( 0-1 mmol/L) Other lab data of note were as follows: Plasma osmolality 300 mOsm/Kg (275-297)); Anion gap >13 mEq/L (<11 mEq/L); WCC 16.7 x109/L(4-11), haematocrit 48%(37-48 ), haemoglobin 14.3 g/dl (12-16),urea 60 mg/dl (7-21),creatinine 1.4 mg/dl (0.6-1.1), Na+ 152 mEq/L(135-147), K+ 5.3 mEq/L(3.5-5.1), A urine specimen was sent for culture following dip stick analysis showing positive results for leucocyte esterase and nitrite. Miss Jones was started on antibiotics(IV cefuroxime). An IV infusion of normal saline was set up followed by Actrapid insulin on a sliding scale. As the patient had the triad of hyperglycaemia, ketosis, and acidosis the diagnosis of DKA was confirmed. Urine culture showed pure growth of Escherichia coli[ > 106 colony forming units/ml (CFU). She was finally diagnosed with urinary tract infection precipitating DKA. Further investigations revealed a haemoglobin A1c 13.8%(4-5.3) , and C-peptide (premeal) 0.441 ng/mL (1.1-4.4 ng/mL). Immunological testing revealed positivity for anti-GAD65, anti-IA2, anti-insulin, anti-ICA, and antiZnT8 antibodies.She was therefore diagnosed as suffering from type 1 diabetes. She made an uneventful recovery with the above management and was discharged with instructions to continue subcutaneous insulin injections for glycemic control. 1.Microbiology questions(20 Marks) The case study states that a pure culture of Escherichia coli was obtained from a urine sample given by the patient. Explain the predisposing factors for urinary tract infection with this organism particularly in patients with diabetes. (10 marks) How could bacterial organisms that could cause urinary tract infections be differentiated in the laboratory? How would this vary depending on the organism if a different pathogen was suspected? (10 marks) 2 Biochemistry questions(20 marks) Explain the abbreviation DKA. Outline the biochemical processes leading from insulin deficiency in type 1 diabetes to DKA. (10 marks) Why was C-peptide measured and what does the low level indicate? What may be deduced about the duration of the patient’s diabetes from the HbA1c measurement? (10 marks)