Cases/Mental Health

Unexplained Electrolyte Abnormalities — Free SCA Practice Case

Young woman with unexplained electrolyte abnormalities

Station Timer

12:00

Golden Minute

Initial Introduction

•Introduce yourself

•Ask an open question — "How can I help you today?"

•Listen — don't interrupt

•Catch early cues

Data Gathering

History, ICE & Diagnosis

Clinical Management

Diagnosis, Plan & Decisions

Safety Net

Follow-up & Close

12:00

Golden Minute

Materials for Candidate

Please review before starting the consultation

Patient Profile

Full Name

Amy Sinclair

Age

24 years

Consultation Type

Telephone

Age

Situation

Telephone Consultation. Seen by a colleague 2 days ago for tiredness and weakness; blood tests are now back and the patient has booked a call to discuss them.

Reason for Encounter

"I've booked to go through my blood results. I've been really tired and weak and I want to know what's wrong — I thought it might be low iron."

Medical Records

●PMH: Nil recorded.
●Medications: None on repeat.
●Allergies: NKDA.
●Colleague's note (2 days ago): Fatigue, muscle weakness, occasional dizziness over ~2 weeks. BP 104/64, pulse 96. Bloods requested.
●Blood results (for filing): Potassium 2.8 mmol/L (low; ref 3.5–5.0); bicarbonate 33 mmol/L (raised; metabolic alkalosis); sodium 137; magnesium low-normal; urea/creatinine/eGFR normal. TFTs, FBC, ferritin, coeliac screen, LFTs, HbA1c, CRP, glucose — normal. Impression: unexplained hypokalaemia with metabolic alkalosis.

Patient Script

For the friend playing the patient role

Character Overview: You are Amy, 24, a primary-school teaching assistant. You have felt tired, weak, and occasionally dizzy for a couple of weeks. You believe it is probably low iron. In fact, you have an eating disorder that you have hidden from everyone, involving purging behaviour, which you feel deep shame about and have never disclosed. You are guarded and will attribute everything to stress or diet at first. Only if the doctor is warm, non-judgemental, and asks sensitively will you begin to open up. You are frightened and relieved in equal measure at the idea of finally telling someone.

Opening Sentence: "Hi Doctor. I'm ringing about my blood results. I've been shattered and a bit weak and dizzy for a couple of weeks — I assumed it was low iron, because that runs in my family. I just want to know what the tests showed."

History if Asked (Data Gathering Phase)

●The symptoms: "Really tired, muscle weakness, and I get light-headed sometimes — like I might faint. It's been about two weeks and it's affecting my work."
●What she thinks it is: "I assumed low iron — I've been a bit run down. Maybe stress; work's been busy."
●Diet/eating (guarded at first, only opens up if asked sensitively): "My eating's been… not great. [guarded] I've been under a lot of pressure about how I look. [long pause, if the doctor is gentle] Honestly… I've been making myself unwell to control my weight. I've never told anyone. I'm so ashamed."
●If the doctor is gentle and non-judgemental: "It's been going on for a while. I feel like it's out of control and I hate myself for it. I didn't think it would end up affecting my blood or my health like this."
●Weight/appetite (kept general — she does not volunteer numbers): "My weight's changed and my clothes fit differently. I'd rather not get into numbers."

ICE — Ideas, Concerns, Expectations

The patient does not volunteer this information unprompted, and the eating disorder emerges only with sensitive, non-judgemental questioning.

●Ideas: Amy has told herself the tiredness is low iron or stress, keeping the real cause hidden even from herself at times. "I've been telling myself it's just iron or stress — anything but the real reason."
●Concerns: Beneath the presenting complaint she is frightened about her health, ashamed of the eating disorder, and terrified of being judged or of losing control of the one thing she feels she controls. "I'm scared something serious is wrong with me, and I'm terrified of anyone finding out and judging me."
●Expectations: She expects to be told she needs iron; she is not expecting, and is anxious about, a conversation about her eating. "I came thinking I'd be told to take iron tablets. I didn't expect to be talking about… this."

If Asked — Screening, Risk, and Medical Assessment (approached sensitively)

The patient answers these only when directly and sensitively asked.

●If asked, sensitively, using a screening approach (e.g. the SCOFF questions) about her relationship with eating and control: "…Yes. I worry about my weight all the time, and I've been doing things to control it that I know aren't healthy."
●If asked about purging or compensatory behaviours (in general clinical terms): "Yes — I have been purging. I don't want to go into detail. I know it's why I feel so ill." (The candidate should not press for method detail.)
●If asked about palpitations, fainting, or chest symptoms: "My heart sometimes races, and I've felt like I might faint — that's frightened me."
●If asked, sensitively, about mood and thoughts of self-harm or that life isn't worth living: "I feel low and trapped, and there have been dark moments… but I wouldn't act on it." (Passive thoughts, no plan; assess sensitively — no method detail sought or given.)
●If asked about how long and whether she has told anyone: "A while now. I've never told a soul. You're the first."
●If asked about support / relationships: "I live alone. My family are close but I've hidden all this from them."
●If asked about medications, laxatives, or other agents (in general terms): "I'd rather not go into specifics, but yes, I've used things to try to control my weight."

Responses to Management (The Negotiation Phase)

●If the Doctor responds to the disclosure with compassion and no judgement: "You're not disgusted with me? [emotional] I've been carrying this on my own for so long." (The tested point is a compassionate, non-judgemental response that makes disclosure safe.)
●If the Doctor explains the blood results are linked to the behaviour and are a medical risk: "So the purging has done this to my blood? Is it dangerous?" (The tested point is explaining that the electrolyte disturbance is a serious medical consequence needing urgent attention, without alarming her destructively.)
●If the Doctor arranges urgent assessment (ECG, potassium, hospital if needed): "I have to be seen today? Is it really that serious?" (The tested point is recognising and acting on the medical risk of the hypokalaemia.)
●If the Doctor refers to eating-disorder services: "There's specialist help for this? I didn't know where to even start."
●If the Doctor discusses telling her family / support: "I don't know how I'd ever tell my family. But keeping it secret is destroying me."

Mark Scheme

Domain 1: Data Gathering and Diagnosis

0 / 16 indicators checked+0−0

Positive (0/8)

Negative (0/8)

Domain 2: Clinical Management and Medical Complexity

0 / 18 indicators checked+0−0

Positive (0/9)

Negative (0/9)

Domain 3: Relating to Others

0 / 12 indicators checked+0−0

Positive (0/6)

Negative (0/6)

Clinical Learning Points

Unexplained Electrolyte Disturbance Can Signal an Eating Disorder

●Unexplained hypokalaemia (often with metabolic alkalosis) in a young person — particularly a young woman — should raise the possibility of purging behaviour and an eating disorder. The biochemistry may be the first and only visible sign of a concealed illness.
●Normal ferritin/FBC excludes the "low iron" the patient may assume.

Eating Disorders Are Frequently Concealed

●Eating disorders are often hidden through profound shame. Sensitive, non-judgemental screening (e.g. the SCOFF questionnaire) and a safe, unhurried manner are essential to enable disclosure — and one should not press for graphic detail of behaviours.

Medical Risk Is the Immediate Priority

●Significant hypokalaemia is potentially life-threatening (cardiac arrhythmia). Arrange an urgent ECG and same-day clinical assessment, correct electrolytes under appropriate supervision, and admit if medically unstable.
●Use a structured medical-risk assessment (the RCPsych MEED guidance — Medical Emergencies in Eating Disorders) to judge urgency.

Treat Both the Medical and the Underlying Disorder

●Correcting electrolytes in isolation is futile and unsafe — the underlying eating disorder must be addressed. Refer to NHS community eating-disorder services (urgently if medically unstable) for specialist multidisciplinary care.

Mental-Health Risk

●Eating disorders carry an elevated risk of self-harm and suicide. Assess mood and risk sensitively (without naming methods) and respond proportionately.

What Not to Do

●Do not issue diet, weight, or exercise targets/plans — these are the specialist team's domain and can be harmful. The GP's role is recognition, medical-risk management, compassionate support, and referral.

Support and Continuity

●Signpost Beat and NHS support; involve family/support with the patient's consent (respecting that control is central to the disorder); provide safety-netting and close follow-up.

Common Candidate Mistakes in This Case

●Missing the eating disorder: treating the hypokalaemia as an isolated finding, or accepting "low iron," and reassuring/prescribing iron.
●Failing to act on the medical risk: not arranging an urgent ECG/assessment for potentially life-threatening hypokalaemia.
●A judgemental or awkward response to disclosure: deepening shame and shutting down engagement.
●Correcting potassium in isolation: ignoring the underlying disorder and specialist referral.
●Giving diet/weight/exercise prescriptions: inappropriate and potentially harmful in an eating disorder.

Free MRCGP SCA practice case for GP registrars covering Unexplained Electrolyte Abnormalities — Mental Health. Includes candidate brief, patient script, marking scheme mapped to the RCGP SCA marking domains, and learning points. Built directly from the RCGP curriculum topic stations listed under "How this might be tested in the MRCGP SCA," part of a free library of 79 SCA practice cases for simulated consultation assessment preparation.

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