A diagnostic perspective Flashcards
The basic model
Its uses requires a disciplined approach to the problem with the GP quickly answering five self-posed questions;
- What is the probability diagnosis?
- What serious disorders must not be missed?
- What conditions are often missed (the pitfalls)?
- Could this pt have one of the ‘masquerades’ in medical practice?
- Is this pt trying to tell me something else?
The probability diagnosis
This is based on;
- the doctor’s perspective
- and experience of prevalence
- incidence
- the natural history of disease
The question is ‘for this particular pt with this specific problem/s presenting today, what is the likely diagnosis?’
What serious disorders must not be missed?
To achieve early recognition of serious illness the GP needs to develop a ‘high index of suspicion’.
This is generally regarded as largely intuitive but is probably not so—it would be more accurate to say that it comes with experience.
The serious disorders that should always be considered ‘until proven otherwise’ can be classified as;
- V—vascular
- I—infection (severe)
- N—neoplasia esp. cancer
What serious disorders must not be missed? eg
MI, or ischaemia, is extremely important to consider as it is so potentially lethal and at times can be overlooked by the busy practitioner.
CAD may also manifest as life-threatening arrhythmias, which may present as palpitations and/or dizziness.
A high index of suspicion is necessary to diagnose arrhythmias
The concept of red flags or ‘alarm bells’ is useful in this context, e.g.:
- age >50
- sudden onset of problem
- history of cancer
- fever >37.8°C
- weight loss
- pallor
- overseas travel
- unusual vomiting
- neurological deficit
- altered cognition/consciousness
- failure to improve
- syncope at toilet
- drug or alcohol abuse
- medication e.g. steroids, biologicals
What conditions are often missed?
This question refers to the common ‘pitfalls’ so often encountered in general practice.
This area is definitely related to the experience factor and includes rather simple non-life-threatening problems that can be so easily overlooked unless doctors are prepared to include them in their diagnostic framework
The masquerades (‘chameleons’)
It is important to use a type of fail-safe mechanism to avoid missing the diagnosis of these disorders.
Some practitioners refer to consultations that make their ‘head spin’ in confusion and bewilderment, with pts presenting with a ‘shopping list’ of undifferentiated or vague problems.
It is with these pts that a checklist is useful.
The seven primary masquerades
- Depression
- Diabetes mellitus
- Drugs
- iatrogenic
- self-abuse
- alcohol
- narcotics
- nicotine
- others
- Anaemia
- Thyroid and other endocrine disorders
- hyperthyroidism
- hypothyroidism
- Addison disease
- Spinal dysfunction
- Urinary infection
The seven other less common masquerades
- Chronic renal failure
- Malignant disease
- lymphomas/leukaemias
- lung
- caecum/colon
- kidney
- multiple myeloma
- ovary
- metastasis
- HIV infection/AIDS
- Baffling bacterial infections
- syphilis
- tuberculosis
- infective endocarditis
- the zoonoses
- Chlamydia infections
- atypical pneumonias
- others
- Baffling viral (and protozoal) infections
- Epstein-Barr mononucleosis
- TORCH organisms (e.g. cytomegalovirus)
- Hepatitis A, B, C, D, E, F, G
- mosquito-borne infections–malaria, Ross River fever, dengue
- others
- Neurological dilemmas
- Parkinson disease
- Guillain–Barre syndrome
- seizure disorders esp. complex partial
- multiple sclerosis
- myasthenia gravis
- space-occupying lesion of skull
- migraine and its variants
- others
- Connective tissue disorders and the vasculitides
- CT disorders–SLE, systemic sclerosis, dermatomyositis, overlap syndrome
- Vasculitides–polyarteritis nodosa, GCA /PMR, granulomatous disorders and others
Is the patient trying to tell me something?
The doctor has to consider, esp. in the case of undifferentiated illness, whether pt has a hidden agenda for the presentation.
Of course, pt may be depressed (overt or masked) or may have a true anxiety state.
However, a presenting symptom such as tiredness may represent a ‘ticket of entry’ to the consulting room.
It may represent a plea for help in a stressed or anxious patient.
Underlying fears or image problems that cause stress and anxiety
- Interpersonal conflict in the family
- Identification with sick or deceased friends
- Fear of malignancy
- STIs, esp. AIDS
- Impending ‘coronary’ or ‘stroke’
- Sexual problem
- Drug-related problem
- Crippling arthritis
- Financial worries
- Other abnormal stressors
What are yellow flags?
Important underlying psychosocial problems are referred to as yellow flags, e.g.
- Munchausen syndrome
- abnormal illness behaviour
- atypical signs
- poor work performance
- law and order incidents
What is the Baseball rule for delayed diagnosis?
Three strikes and you’re out—refer.
