Cavity, OHA, Metformin

1. If you see a cavity in the CXR, what are the differential diagnosis? Please list out at least 5 diff diagnosis.

2. What does "OHA" mean? (clue: OHA is a short-formed.)

3. What is Metformin and its maximum dosage?

Differential diagnosis for cavity on CXR:

1. Primary lung cancer
2. Pulmonary tuberculosis (PTB)
3. Abscess formation in pneumonia
4. Lung infarction due to pulmonary embolism
5. Fungal disease: e.g. Aspergillosis
6. Lung cyst

OHA = Oral Hypoglycemic Agent, drug for type 2 diabetes mellitus.

Metformin is an biguanide OHA, maximum dose is 1g per dose 8 hourly. 

--- UPDATE ---

The answer would be:

1. Cavity in the CXR:

- Bronchial CA(carcinoma); most likely SCC (squamous cell carcinoma- one type of non small cell CA)

(Extra: Lung CA is divided into small cell CA and non-small cell CA; non small cell CA is further subdivided into 3 types-> SCC, adenocarcinoma and undifferentiated lung CA)

- Lung abscess

- Pneumonia caused by microorganisms mainly of Klebsiella pneumonia and Staphylococcus aerus.

- Fungal lung disease, eg aspergilloma

- PTB (pulmonary tuberculosis)

- Wegener's granulomatosis

2. OHA is oral hypoglycemic agent

3. Metformin is biguanide for DM type II.
Maximum dosage would 1g tds(8 hourly)

- Contraindicated in liver and kidney impairment and congestive heart failure(CCF), lactic acidosis.

- Usually in practise, if creatine reaches 150 mcgmol/L, then it must be discontinued. 

- Usage starting dosage would be 250mg BD up to 1g tds