Learn Hardcore Indonesian: Konsultasi pertama dia dengan dokter spesialis itu membuatnya lebih tenang. - Her first consultation with that specialist doctor makes her calmer.

If you say konsultasi dia yang pertama, it is still grammatical, but it sounds a bit heavier and more contrastive (emphasising the one that is first among several of his/her consultations). The original konsultasi pertama dia is more neutral and natural here.

What role does itu play in "dokter spesialis itu", and why does it come after the noun?

Itu is a demonstrative; here it works like that or the in English, pointing to a specific doctor that the speaker and listener already know about.

Indonesian noun phrase order is:

noun (and its modifiers) + ini/itu

So:

dokter = doctor
spesialis = specialist
dokter spesialis = specialist doctor
dokter spesialis itu = that / the specialist doctor (that one we’ve talked about / can identify)

You don't say itu dokter spesialis for this meaning; that would usually be a full clause:

Itu dokter spesialis. = That (person) is a specialist doctor.

What’s the difference between dia and -nya in this sentence: dia in konsultasi pertama dia vs *membuatnya?

Both refer to a 3rd person (he/she), but they have different grammatical roles and positions.

dia is an independent pronoun, used as subject or possessor:
- Dia datang. = He/She came.
- konsultasi pertama dia = his/her first consultation.
-nya is a clitic (attached pronoun), often marking an object or a possessor:
- membuatnya = membuat + -nya = make him/her
- bukunya = buku + -nya = his/her/their book / the book.

In membuatnya, -nya is the object of membuat. You could also say:

membuat dia lebih tenang = make him/her calmer
membuatnya lebih tenang = same meaning, slightly smoother and more compact.

In konsultasi pertama dia, -nya is not used because dia here is the possessor after a noun. You could say konsultasi pertamanya (his/her first consultation), but that slightly shifts emphasis (see next question).

Can we say "konsultasi pertamanya" instead of "konsultasi pertama dia"? Is there any difference?

Yes, both are grammatical, but there is a nuance:

konsultasi pertama dia = his/her first consultation (more neutral, slightly more spoken feel).
konsultasi pertamanya = his/her first consultation (a bit more compact and often feels a bit more narrative/written or slightly more definite, like the first consultation we’ve been referring to).

In this sentence:

Konsultasi pertama dia dengan dokter spesialis itu membuatnya lebih tenang.

You could replace it with:

Konsultasi pertamanya dengan dokter spesialis itu membuatnya lebih tenang.

The core meaning is the same. The version with -nya can sound a bit more cohesive, as if we are following his/her story in a narrative.

What is the grammatical pattern of "membuatnya lebih tenang"? How does membuat work here?

Here the verb membuat = to make / cause, and it’s used in a causative pattern:

membuat + object + adjective/state

So:

membuatnya = make him/her
lebih tenang = more calm

Together:

membuatnya lebih tenang = made him/her calmer or made him/her feel calmer.

This pattern is very common:

Berita itu membuat saya sedih. = That news made me sad.
Senyumannya membuat mereka bahagia. = Her smile made them happy.

You can add merasa explicitly:

membuatnya merasa lebih tenang = made him/her feel calmer,

but it’s not required; membuatnya lebih tenang already implies the feeling.

Why is "lebih" used before "tenang"? Can we say only "tenang"?

tenang = calm
lebih = more / rather / comparatively

lebih tenang literally means more calm / calmer. In context, it usually means:

calmer than before,
or somewhat calmer / more at ease.

If you say:

membuatnya tenang = made him/her calm (sounds like reaching a calm state)
membuatnya lebih tenang = made him/her calmer (compared to a previous, more anxious state).

Because this is the first consultation, lebih tenang nicely implies a change from being more anxious to being calmer afterward.

Why isn’t there any "adalah" or "ialah" in this sentence?

Adalah/ialah are copular markers (similar to is/are) mainly used in equational sentences (X = Y), like:

Dia adalah dokter. = He/She is a doctor.

Your sentence is not an equational sentence; it has a clear verb:

Konsultasi pertama dia ... membuatnya lebih tenang.

The main verb is membuat (to make). The structure is:

Subject: Konsultasi pertama dia dengan dokter spesialis itu
Verb: membuat (inside membuatnya)
Object: -nya (him/her)
Complement: lebih tenang

Since there is already a lexical verb (membuat), no adalah is needed or possible here.

Can dia be omitted anywhere? For example, can we say "Konsultasi pertama dengan dokter spesialis itu membuatnya lebih tenang"?

Yes, that’s possible if the context is clear:

Konsultasi pertama dengan dokter spesialis itu membuatnya lebih tenang.

Here konsultasi pertama is understood as his/her first consultation from context, and -nya in membuatnya still refers to the same person.

However:

Including dia (konsultasi pertama dia) makes the possessor explicit in the noun phrase.
Omitting it relies more on prior context (we must already know whose consultation we are talking about).

Both versions are acceptable; the original is just slightly more explicit and clear in isolation.

What is the difference between "dokter spesialis" and just "spesialis"?

dokter spesialis = specialist doctor (a medical doctor with a specialization).
spesialis alone can mean specialist more generally (not necessarily a medical doctor) or can still refer to a medical specialist depending on context.

In everyday medical context, dokter spesialis clearly indicates:

a medical doctor who has specialized in a certain field (e.g., dokter spesialis jantung, cardiologist).

Using the fuller dokter spesialis here makes it unambiguously medical and a bit more formal.

How does "konsultasi pertama dia dengan dokter spesialis itu" hang together structurally? What modifies what?

The whole chunk is one long noun phrase functioning as the subject.

Breakdown:

konsultasi = head noun (consultation)
pertama = adjective/numeral modifier (first)
dia = possessor (his/her)
dengan dokter spesialis itu = prepositional phrase modifying konsultasi (with that specialist doctor)

So, structurally:

[konsultasi [pertama] [dia]] [dengan [dokter spesialis itu]]

Meaning:

his/her first consultation with that specialist doctor

The whole thing is then the subject of membuatnya lebih tenang.

Is this sentence formal, informal, or neutral? How might it look in more colloquial Indonesian?

The original sentence is neutral to slightly formal, suitable for writing, stories, or polite conversation:

Konsultasi pertama dia dengan dokter spesialis itu membuatnya lebih tenang.

A more colloquial/relaxed version (especially in Jakarta-style speech) might be:

Konsultasi pertama dia sama dokter spesialis itu bikin dia lebih tenang.

Changes:

dengan → sama (more colloquial with),
membuatnya → bikin dia (colloquial make him/her),
sometimes dia → dia/dia-nya/-nya depending on style.

The meaning stays the same; only the register changes.